[TASK]
You will be given four numbers and a target number, your task is to find a way to use all four numbers exactly once, along with the basic operations (+, -, *, /), to reach the target number.

[RULES]
- You can use each number exactly once.
- You can use the four basic operations (+, -, *, /).
- The intermediate results must be integers (no decimals allowed).
- The intermediate results must be positive.
- The intermediate results will not exceed 2000.

[APPROACH]
We will solve the problem by searching. Starting from a given set of four numbers, we will follow this search process:
- At each state, we will consider all possible number pairs (in order) from the current number set. Choose one pair and apply one of the four basic operations to them to obtain a new number.
  * If there are still numbers left, we will add the new number to the number set and continue the search.
  * If we have used all numbers, we will check if the new number is equal to the target number. If it is, we have found the solution. Otherwise, we will backtrack.
- Suppose the two numbers we choose are a and b (where a >= b). We will try the four options (a + b), (a - b), (a * b), (a / b) to obtain the new number. Remember to always use the larger number as the first operand.
- If the new number is a decimal, or exceeds the maximum intermediate result, we will discard this branch and backtrack.
- We will continue this process until we reach the target number with four numbers used or exhaust all possible combinations.

[EXAMPLES]
# Example
Numbers: [40, 19, 23, 7]
Target: 29

# Search Procedure
Initial number set: [40, 19, 23, 7], target: 29. Options for choosing two numbers: [(40, 19), (40, 23), (40, 7), (19, 23), (19, 7), (23, 7)].
 |- Pick two numbers (40, 19) (numbers left: [23, 7]). Try possible operations.
  |- Try 40 + 19 = 59. Add 59 to the number set. Current number set: [59, 23, 7], target: 29. Options for choosing two numbers: [(59, 23), (59, 7), (23, 7)].
   |- Pick two numbers (59, 23) (numbers left: [7]). Try possible operations.
    |- Try 59 + 23 = 82. Add 82 to the number set. Current number set: [82, 7], target: 29, just two numbers left.
     |- Try 82 + 7 = 89. Evaluate 89 != 29, drop this branch.
     |- Try 82 - 7 = 75. Evaluate 75 != 29, drop this branch.
     |- Try 82 * 7 = 574. Evaluate 574 != 29, drop this branch.
     |- Try 82 / 7 = 11.7. 11.7 is a decimal, drop this branch.
    |- Try 59 - 23 = 36. Add 36 to the number set. Current number set: [36, 7], target: 29, just two numbers left.
     |- Try 36 + 7 = 43. Evaluate 43 != 29, drop this branch.
     |- Try 36 - 7 = 29. Evaluate 29 == 29, target found!

Now we have found the target, let's trace back the solution:
Final step: 36 - 7 = 29
The step before: 59 - 23 = 36
The first step: 40 + 19 = 59

Output the solution in the required format:
<Solution>
40 + 19 = 59
59 - 23 = 36
36 - 7 = 29
</Solution>

# Example
Numbers: [9, 16, 6, 18]
Target: 12

# Search Procedure
Initial number set: [9, 16, 6, 18], target: 12. Options for choosing two numbers: [(9, 16), (9, 6), (9, 18), (16, 6), (16, 18), (6, 18)].
 |- Pick two numbers (9, 16) (numbers left: [6, 18]). Try possible operations.
  |- Try 16 + 9 = 25. Add 25 to the number set. Current number set: [25, 6, 18], target: 12. Options for choosing two numbers: [(25, 6), (25, 18), (6, 18)].
   |- Pick two numbers (25, 6) (numbers left: [18]). Try possible operations.
    |- Try 25 + 6 = 31. Add 31 to the number set. Current number set: [31, 18], target: 12, just two numbers left.
     |- Try 31 + 18 = 49. Evaluate 49 != 12, drop this branch.
     |- Try 31 - 18 = 13. Evaluate 13 != 12, drop this branch.
     |- Try 31 * 18 = 558. Evaluate 558 != 12, drop this branch.
     |- Try 31 / 18 = 1.7. 1.7 is a decimal, drop this branch.
    |- Try 25 - 6 = 19. Add 19 to the number set. Current number set: [19, 18], target: 12, just two numbers left.
     |- Try 19 + 18 = 37. Evaluate 37 != 12, drop this branch.
     |- Try 19 - 18 = 1. Evaluate 1 != 12, drop this branch.
     |- Try 19 * 18 = 342. Evaluate 342 != 12, drop this branch.
     |- Try 19 / 18 = 1.1. 1.1 is a decimal, drop this branch.
    |- Try 25 * 6 = 150. Add 150 to the number set. Current number set: [150, 18], target: 12, just two numbers left.
     |- Try 150 + 18 = 168. Evaluate 168 != 12, drop this branch.
     |- Try 150 - 18 = 132. Evaluate 132 != 12, drop this branch.
     |- Try 150 * 18 = 2700. 2700 exceeds the maximum intermediate result, drop this branch.
     |- Try 150 / 18 = 8.3. 8.3 is a decimal, drop this branch.
    |- Try 25 / 6 = 4.2. 4.2 is a decimal, drop this branch.
   |- Pick two numbers (25, 18) (numbers left: [6]). Try possible operations.
    |- Try 25 + 18 = 43. Add 43 to the number set. Current number set: [43, 6], target: 12, just two numbers left.
     |- Try 43 + 6 = 49. Evaluate 49 != 12, drop this branch.
     |- Try 43 - 6 = 37. Evaluate 37 != 12, drop this branch.
     |- Try 43 * 6 = 258. Evaluate 258 != 12, drop this branch.
     |- Try 43 / 6 = 7.2. 7.2 is a decimal, drop this branch.
    |- Try 25 - 18 = 7. Add 7 to the number set. Current number set: [7, 6], target: 12, just two numbers left.
     |- Try 7 + 6 = 13. Evaluate 13 != 12, drop this branch.
     |- Try 7 - 6 = 1. Evaluate 1 != 12, drop this branch.
     |- Try 7 * 6 = 42. Evaluate 42 != 12, drop this branch.
     |- Try 7 / 6 = 1.2. 1.2 is a decimal, drop this branch.
    |- Try 25 * 18 = 450. Add 450 to the number set. Current number set: [450, 6], target: 12, just two numbers left.
     |- Try 450 + 6 = 456. Evaluate 456 != 12, drop this branch.
     |- Try 450 - 6 = 444. Evaluate 444 != 12, drop this branch.
     |- Try 450 * 6 = 2700. 2700 exceeds the maximum intermediate result, drop this branch.
     |- Try 450 / 6 = 75. Evaluate 75 != 12, drop this branch.
    |- Try 25 / 18 = 1.4. 1.4 is a decimal, drop this branch.
   |- Pick two numbers (6, 18) (numbers left: [25]). Try possible operations.
    |- Try 18 + 6 = 24. Add 24 to the number set. Current number set: [24, 25], target: 12, just two numbers left.
     |- Try 25 + 24 = 49. Evaluate 49 != 12, drop this branch.
     |- Try 25 - 24 = 1. Evaluate 1 != 12, drop this branch.
     |- Try 25 * 24 = 600. Evaluate 600 != 12, drop this branch.
     |- Try 25 / 24 = 1.0. 1.0 is a decimal, drop this branch.
    |- Try 18 - 6 = 12. Add 12 to the number set. Current number set: [12, 25], target: 12, just two numbers left.
     |- Try 25 + 12 = 37. Evaluate 37 != 12, drop this branch.
     |- Try 25 - 12 = 13. Evaluate 13 != 12, drop this branch.
     |- Try 25 * 12 = 300. Evaluate 300 != 12, drop this branch.
     |- Try 25 / 12 = 2.1. 2.1 is a decimal, drop this branch.
    |- Try 18 * 6 = 108. Add 108 to the number set. Current number set: [108, 25], target: 12, just two numbers left.
     |- Try 108 + 25 = 133. Evaluate 133 != 12, drop this branch.
     |- Try 108 - 25 = 83. Evaluate 83 != 12, drop this branch.
     |- Try 108 * 25 = 2700. 2700 exceeds the maximum intermediate result, drop this branch.
     |- Try 108 / 25 = 4.3. 4.3 is a decimal, drop this branch.
    |- Try 18 / 6 = 3. Add 3 to the number set. Current number set: [3, 25], target: 12, just two numbers left.
     |- Try 25 + 3 = 28. Evaluate 28 != 12, drop this branch.
     |- Try 25 - 3 = 22. Evaluate 22 != 12, drop this branch.
     |- Try 25 * 3 = 75. Evaluate 75 != 12, drop this branch.
     |- Try 25 / 3 = 8.3. 8.3 is a decimal, drop this branch.
  |- Try 16 - 9 = 7. Add 7 to the number set. Current number set: [7, 6, 18], target: 12. Options for choosing two numbers: [(7, 6), (7, 18), (6, 18)].
   |- Pick two numbers (7, 6) (numbers left: [18]). Try possible operations.
    |- Try 7 + 6 = 13. Add 13 to the number set. Current number set: [13, 18], target: 12, just two numbers left.
     |- Try 18 + 13 = 31. Evaluate 31 != 12, drop this branch.
     |- Try 18 - 13 = 5. Evaluate 5 != 12, drop this branch.
     |- Try 18 * 13 = 234. Evaluate 234 != 12, drop this branch.
     |- Try 18 / 13 = 1.4. 1.4 is a decimal, drop this branch.
    |- Try 7 - 6 = 1. Add 1 to the number set. Current number set: [1, 18], target: 12, just two numbers left.
     |- Try 18 + 1 = 19. Evaluate 19 != 12, drop this branch.
     |- Try 18 - 1 = 17. Evaluate 17 != 12, drop this branch.
     |- Try 18 * 1 = 18. Evaluate 18 != 12, drop this branch.
     |- Try 18 / 1 = 18. Evaluate 18 != 12, drop this branch.
    |- Try 7 * 6 = 42. Add 42 to the number set. Current number set: [42, 18], target: 12, just two numbers left.
     |- Try 42 + 18 = 60. Evaluate 60 != 12, drop this branch.
     |- Try 42 - 18 = 24. Evaluate 24 != 12, drop this branch.
     |- Try 42 * 18 = 756. Evaluate 756 != 12, drop this branch.
     |- Try 42 / 18 = 2.3. 2.3 is a decimal, drop this branch.
    |- Try 7 / 6 = 1.2. 1.2 is a decimal, drop this branch.
   |- Pick two numbers (7, 18) (numbers left: [6]). Try possible operations.
    |- Try 18 + 7 = 25. Add 25 to the number set. Current number set: [25, 6], target: 12, just two numbers left.
     |- Try 25 + 6 = 31. Evaluate 31 != 12, drop this branch.
     |- Try 25 - 6 = 19. Evaluate 19 != 12, drop this branch.
     |- Try 25 * 6 = 150. Evaluate 150 != 12, drop this branch.
     |- Try 25 / 6 = 4.2. 4.2 is a decimal, drop this branch.
    |- Try 18 - 7 = 11. Add 11 to the number set. Current number set: [11, 6], target: 12, just two numbers left.
     |- Try 11 + 6 = 17. Evaluate 17 != 12, drop this branch.
     |- Try 11 - 6 = 5. Evaluate 5 != 12, drop this branch.
     |- Try 11 * 6 = 66. Evaluate 66 != 12, drop this branch.
     |- Try 11 / 6 = 1.8. 1.8 is a decimal, drop this branch.
    |- Try 18 * 7 = 126. Add 126 to the number set. Current number set: [126, 6], target: 12, just two numbers left.
     |- Try 126 + 6 = 132. Evaluate 132 != 12, drop this branch.
     |- Try 126 - 6 = 120. Evaluate 120 != 12, drop this branch.
     |- Try 126 * 6 = 756. Evaluate 756 != 12, drop this branch.
     |- Try 126 / 6 = 21. Evaluate 21 != 12, drop this branch.
    |- Try 18 / 7 = 2.6. 2.6 is a decimal, drop this branch.
   |- Pick two numbers (6, 18) (numbers left: [7]). Try possible operations.
    |- Try 18 + 6 = 24. Add 24 to the number set. Current number set: [24, 7], target: 12, just two numbers left.
     |- Try 24 + 7 = 31. Evaluate 31 != 12, drop this branch.
     |- Try 24 - 7 = 17. Evaluate 17 != 12, drop this branch.
     |- Try 24 * 7 = 168. Evaluate 168 != 12, drop this branch.
     |- Try 24 / 7 = 3.4. 3.4 is a decimal, drop this branch.
    |- Try 18 - 6 = 12. Add 12 to the number set. Current number set: [12, 7], target: 12, just two numbers left.
     |- Try 12 + 7 = 19. Evaluate 19 != 12, drop this branch.
     |- Try 12 - 7 = 5. Evaluate 5 != 12, drop this branch.
     |- Try 12 * 7 = 84. Evaluate 84 != 12, drop this branch.
     |- Try 12 / 7 = 1.7. 1.7 is a decimal, drop this branch.
    |- Try 18 * 6 = 108. Add 108 to the number set. Current number set: [108, 7], target: 12, just two numbers left.
     |- Try 108 + 7 = 115. Evaluate 115 != 12, drop this branch.
     |- Try 108 - 7 = 101. Evaluate 101 != 12, drop this branch.
     |- Try 108 * 7 = 756. Evaluate 756 != 12, drop this branch.
     |- Try 108 / 7 = 15.4. 15.4 is a decimal, drop this branch.
    |- Try 18 / 6 = 3. Add 3 to the number set. Current number set: [3, 7], target: 12, just two numbers left.
     |- Try 7 + 3 = 10. Evaluate 10 != 12, drop this branch.
     |- Try 7 - 3 = 4. Evaluate 4 != 12, drop this branch.
     |- Try 7 * 3 = 21. Evaluate 21 != 12, drop this branch.
     |- Try 7 / 3 = 2.3. 2.3 is a decimal, drop this branch.
  |- Try 16 * 9 = 144. Add 144 to the number set. Current number set: [144, 6, 18], target: 12. Options for choosing two numbers: [(144, 6), (144, 18), (6, 18)].
   |- Pick two numbers (144, 6) (numbers left: [18]). Try possible operations.
    |- Try 144 + 6 = 150. Add 150 to the number set. Current number set: [150, 18], target: 12, just two numbers left.
     |- Try 150 + 18 = 168. Evaluate 168 != 12, drop this branch.
     |- Try 150 - 18 = 132. Evaluate 132 != 12, drop this branch.
     |- Try 150 * 18 = 2700. 2700 exceeds the maximum intermediate result, drop this branch.
     |- Try 150 / 18 = 8.3. 8.3 is a decimal, drop this branch.
    |- Try 144 - 6 = 138. Add 138 to the number set. Current number set: [138, 18], target: 12, just two numbers left.
     |- Try 138 + 18 = 156. Evaluate 156 != 12, drop this branch.
     |- Try 138 - 18 = 120. Evaluate 120 != 12, drop this branch.
     |- Try 138 * 18 = 2484. 2484 exceeds the maximum intermediate result, drop this branch.
     |- Try 138 / 18 = 7.7. 7.7 is a decimal, drop this branch.
    |- Try 144 * 6 = 864. Add 864 to the number set. Current number set: [864, 18], target: 12, just two numbers left.
     |- Try 864 + 18 = 882. Evaluate 882 != 12, drop this branch.
     |- Try 864 - 18 = 846. Evaluate 846 != 12, drop this branch.
     |- Try 864 * 18 = 15552. 15552 exceeds the maximum intermediate result, drop this branch.
     |- Try 864 / 18 = 48. Evaluate 48 != 12, drop this branch.
    |- Try 144 / 6 = 24. Add 24 to the number set. Current number set: [24, 18], target: 12, just two numbers left.
     |- Try 24 + 18 = 42. Evaluate 42 != 12, drop this branch.
     |- Try 24 - 18 = 6. Evaluate 6 != 12, drop this branch.
     |- Try 24 * 18 = 432. Evaluate 432 != 12, drop this branch.
     |- Try 24 / 18 = 1.3. 1.3 is a decimal, drop this branch.
   |- Pick two numbers (144, 18) (numbers left: [6]). Try possible operations.
    |- Try 144 + 18 = 162. Add 162 to the number set. Current number set: [162, 6], target: 12, just two numbers left.
     |- Try 162 + 6 = 168. Evaluate 168 != 12, drop this branch.
     |- Try 162 - 6 = 156. Evaluate 156 != 12, drop this branch.
     |- Try 162 * 6 = 972. Evaluate 972 != 12, drop this branch.
     |- Try 162 / 6 = 27. Evaluate 27 != 12, drop this branch.
    |- Try 144 - 18 = 126. Add 126 to the number set. Current number set: [126, 6], target: 12, just two numbers left.
     |- Try 126 + 6 = 132. Evaluate 132 != 12, drop this branch.
     |- Try 126 - 6 = 120. Evaluate 120 != 12, drop this branch.
     |- Try 126 * 6 = 756. Evaluate 756 != 12, drop this branch.
     |- Try 126 / 6 = 21. Evaluate 21 != 12, drop this branch.
    |- Try 144 * 18 = 2592. 2592 exceeds the maximum intermediate result, drop this branch.
    |- Try 144 / 18 = 8. Add 8 to the number set. Current number set: [8, 6], target: 12, just two numbers left.
     |- Try 8 + 6 = 14. Evaluate 14 != 12, drop this branch.
     |- Try 8 - 6 = 2. Evaluate 2 != 12, drop this branch.
     |- Try 8 * 6 = 48. Evaluate 48 != 12, drop this branch.
     |- Try 8 / 6 = 1.3. 1.3 is a decimal, drop this branch.
   |- Pick two numbers (6, 18) (numbers left: [144]). Try possible operations.
    |- Try 18 + 6 = 24. Add 24 to the number set. Current number set: [24, 144], target: 12, just two numbers left.
     |- Try 144 + 24 = 168. Evaluate 168 != 12, drop this branch.
     |- Try 144 - 24 = 120. Evaluate 120 != 12, drop this branch.
     |- Try 144 * 24 = 3456. 3456 exceeds the maximum intermediate result, drop this branch.
     |- Try 144 / 24 = 6. Evaluate 6 != 12, drop this branch.
    |- Try 18 - 6 = 12. Add 12 to the number set. Current number set: [12, 144], target: 12, just two numbers left.
     |- Try 144 + 12 = 156. Evaluate 156 != 12, drop this branch.
     |- Try 144 - 12 = 132. Evaluate 132 != 12, drop this branch.
     |- Try 144 * 12 = 1728. Evaluate 1728 != 12, drop this branch.
     |- Try 144 / 12 = 12. Evaluate 12 == 12, target found!

Now we have found the target, let's trace back the solution:
Final step: 144 / 12 = 12
The step before: 18 - 6 = 12
The first step: 16 * 9 = 144

Output the solution in the required format:
<Solution>
16 * 9 = 144
18 - 6 = 12
144 / 12 = 12
</Solution>

[Problem]
Now, solve the following problem. Note that:
- Please carefully read the approach and examples provided above, and follow them to solve the problem.
- Please ALWAYS include your search procedure (after # Search Procedure). The search procedure should follow the format of the examples provided above.
- Please mark your answer with <Solution> and </Solution> tags. The solution should be a sequence of three equations exactly following the format of the examples above, with no additional text in between.

Numbers: [11, 29, 16, 38]
Target: 36

# Search Procedure
Initial number set: [11, 29, 16, 38], target: 36. Options for choosing two numbers: [(11, 29), (11, 16), (11, 38), (29, 16), (29, 38), (16, 38)].
 |- Pick two numbers (11, 29) (numbers left: [16, 38]). Try possible operations.
  |- Try 29 + 11 = 40. Add 40 to the number set. Current number set: [40, 16, 38], target: 36. Options for choosing two numbers: [(40, 16), (40, 38), (16, 38)].
   |- Pick two numbers (40, 16) (numbers left: [38]). Try possible operations.
    |- Try 40 + 16 = 56. Add 56 to the number set. Current number set: [56, 38], target: 36, just two numbers left.
     |- Try 56 + 38 = 94. Evaluate 94 != 36, drop this branch.
     |- Try 56 - 38 = 18. Evaluate 18 != 36, drop this branch.
     |- Try 56 * 38 = 2128. 2128 exceeds the maximum intermediate result, drop this branch.
     |- Try 56 / 38 = 1.5. 1.5 is a decimal, drop this branch.
    |- Try 40 - 16 = 24. Add 24 to the number set. Current number set: [24, 38], target: 36, just two numbers left.
     |- Try 38 + 24 = 62. Evaluate 62 != 36, drop this branch.
     |- Try 38 - 24 = 14. Evaluate 14 != 36, drop this branch.
     |- Try 38 * 24 = 912. Evaluate 912 != 36, drop this branch.
     |- Try 38 / 24 = 1.6. 1.6 is a decimal, drop this branch.
    |- Try 40 * 16 = 640. Add 640 to the number set. Current number set: [640, 38], target: 36, just two numbers left.
     |- Try 640 + 38 = 678. Evaluate 678 != 36, drop this branch.
     |- Try 640 - 38 = 602. Evaluate 602 != 36, drop this branch.
     |- Try 640 * 38 = 24320. 24320 exceeds the maximum intermediate result, drop this branch.
     |- Try 640 / 38 = 16.8. 16.8 is a decimal, drop this branch.
    |- Try 40 / 16 = 2.5. 2.5 is a decimal, drop this branch.
   |- Pick two numbers (40, 38) (numbers left: [16]). Try possible operations.
    |- Try 40 + 38 = 78. Add 78 to the number set. Current number set: [78, 16], target: 36, just two numbers left.
     |- Try 78 + 16 = 94. Evaluate 94 != 36, drop this branch.
     |- Try 78 - 16 = 62. Evaluate 62 != 36, drop this branch.
     |- Try 78 * 16 = 1248. Evaluate 1248 != 36, drop this branch.
     |- Try 78 / 16 = 4.9. 4.9 is a decimal, drop this branch.
    |- Try 40 - 38 = 2. Add 2 to the number set. Current number set: [2, 16], target: 36, just two numbers left.
     |- Try 16 + 2 = 18. Evaluate 18 != 36, drop this branch.
     |- Try 16 - 2 = 14. Evaluate 14 != 36, drop this branch.
     |- Try 16 * 2 = 32. Evaluate 32 != 36, drop this branch.
     |- Try 16 / 2 = 8. Evaluate 8 != 36, drop this branch.
    |- Try 40 * 38 = 1520. Add 1520 to the number set. Current number set: [1520, 16], target: 36, just two numbers left.
     |- Try 1520 + 16 = 1536. Evaluate 1536 != 36, drop this branch.
     |- Try 1520 - 16 = 1504. Evaluate 1504 != 36, drop this branch.
     |- Try 1520 * 16 = 24320. 24320 exceeds the maximum intermediate result, drop this branch.
     |- Try 1520 / 16 = 95. Evaluate 95 != 36, drop this branch.
    |- Try 40 / 38 = 1.1. 1.1 is a decimal, drop this branch.
   |- Pick two numbers (16, 38) (numbers left: [40]). Try possible operations.
    |- Try 38 + 16 = 54. Add 54 to the number set. Current number set: [54, 40], target: 36, just two numbers left.
     |- Try 54 + 40 = 94. Evaluate 94 != 36, drop this branch.
     |- Try 54 - 40 = 14. Evaluate 14 != 36, drop this branch.
     |- Try 54 * 40 = 2160. 2160 exceeds the maximum intermediate result, drop this branch.
     |- Try 54 / 40 = 1.4. 1.4 is a decimal, drop this branch.
    |- Try 38 - 16 = 22. Add 22 to the number set. Current number set: [22, 40], target: 36, just two numbers left.
     |- Try 40 + 22 = 62. Evaluate 62 != 36, drop this branch.
     |- Try 40 - 22 = 18. Evaluate 18 != 36, drop this branch.
     |- Try 40 * 22 = 880. Evaluate 880 != 36, drop this branch.
     |- Try 40 / 22 = 1.8. 1.8 is a decimal, drop this branch.
    |- Try 38 * 16 = 608. Add 608 to the number set. Current number set: [608, 40], target: 36, just two numbers left.
     |- Try 608 + 40 = 648. Evaluate 648 != 36, drop this branch.
     |- Try 608 - 40 = 568. Evaluate 568 != 36, drop this branch.
     |- Try 608 * 40 = 24320. 24320 exceeds the maximum intermediate result, drop this branch.
     |- Try 608 / 40 = 15.2. 15.2 is a decimal, drop this branch.
    |- Try 38 / 16 = 2.4. 2.4 is a decimal, drop this branch.
  |- Try 29 - 11 = 18. Add 18 to the number set. Current number set: [18, 16, 38], target: 36. Options for choosing two numbers: [(18, 16), (18, 38), (16, 38)].
   |- Pick two numbers (18, 16) (numbers left: [38]). Try possible operations.
    |- Try 18 + 16 = 34. Add 34 to the number set. Current number set: [34, 38], target: 36, just two numbers left.
     |- Try 38 + 34 = 72. Evaluate 72 != 36, drop this branch.
     |- Try 38 - 34 = 4. Evaluate 4 != 36, drop this branch.
     |- Try 38 * 34 = 1292. Evaluate 1292 != 36, drop this branch.
     |- Try 38 / 34 = 1.1. 1.1 is a decimal, drop this branch.
    |- Try 18 - 16 = 2. Add 2 to the number set. Current number set: [2, 38], target: 36, just two numbers left.
     |- Try 38 + 2 = 40. Evaluate 40 != 36, drop this branch.
     |- Try 38 - 2 = 36. Evaluate 36 == 36, target found!

Now we have found the target, let's trace back the solution:
Final step: 38 - 2 = 36
The step before: 18 - 16 = 2
The first step: 29 - 11 = 18

Output the solution in the required format:
<Solution>
29 - 11 = 18
18 - 16 = 2
38 - 2 = 36
</Solution>

Solution:
29 - 11 = 18
18 - 16 = 2
38 - 2 = 36


[TASK]
You will be given four numbers and a target number, your task is to find a way to use all four numbers exactly once, along with the basic operations (+, -, *, /), to reach the target number.

[RULES]
- You can use each number exactly once.
- You can use the four basic operations (+, -, *, /).
- The intermediate results must be integers (no decimals allowed).
- The intermediate results must be positive.
- The intermediate results will not exceed 2000.

[APPROACH]
We will solve the problem by searching. Starting from a given set of four numbers, we will follow this search process:
- At each state, we will consider all possible number pairs (in order) from the current number set. Choose one pair and apply one of the four basic operations to them to obtain a new number.
  * If there are still numbers left, we will add the new number to the number set and continue the search.
  * If we have used all numbers, we will check if the new number is equal to the target number. If it is, we have found the solution. Otherwise, we will backtrack.
- Suppose the two numbers we choose are a and b (where a >= b). We will try the four options (a + b), (a - b), (a * b), (a / b) to obtain the new number. Remember to always use the larger number as the first operand.
- If the new number is a decimal, or exceeds the maximum intermediate result, we will discard this branch and backtrack.
- We will continue this process until we reach the target number with four numbers used or exhaust all possible combinations.

[EXAMPLES]
# Example
Numbers: [40, 19, 23, 7]
Target: 29

# Search Procedure
Initial number set: [40, 19, 23, 7], target: 29. Options for choosing two numbers: [(40, 19), (40, 23), (40, 7), (19, 23), (19, 7), (23, 7)].
 |- Pick two numbers (40, 19) (numbers left: [23, 7]). Try possible operations.
  |- Try 40 + 19 = 59. Add 59 to the number set. Current number set: [59, 23, 7], target: 29. Options for choosing two numbers: [(59, 23), (59, 7), (23, 7)].
   |- Pick two numbers (59, 23) (numbers left: [7]). Try possible operations.
    |- Try 59 + 23 = 82. Add 82 to the number set. Current number set: [82, 7], target: 29, just two numbers left.
     |- Try 82 + 7 = 89. Evaluate 89 != 29, drop this branch.
     |- Try 82 - 7 = 75. Evaluate 75 != 29, drop this branch.
     |- Try 82 * 7 = 574. Evaluate 574 != 29, drop this branch.
     |- Try 82 / 7 = 11.7. 11.7 is a decimal, drop this branch.
    |- Try 59 - 23 = 36. Add 36 to the number set. Current number set: [36, 7], target: 29, just two numbers left.
     |- Try 36 + 7 = 43. Evaluate 43 != 29, drop this branch.
     |- Try 36 - 7 = 29. Evaluate 29 == 29, target found!

Now we have found the target, let's trace back the solution:
Final step: 36 - 7 = 29
The step before: 59 - 23 = 36
The first step: 40 + 19 = 59

Output the solution in the required format:
<Solution>
40 + 19 = 59
59 - 23 = 36
36 - 7 = 29
</Solution>

# Example
Numbers: [9, 16, 6, 18]
Target: 12

# Search Procedure
Initial number set: [9, 16, 6, 18], target: 12. Options for choosing two numbers: [(9, 16), (9, 6), (9, 18), (16, 6), (16, 18), (6, 18)].
 |- Pick two numbers (9, 16) (numbers left: [6, 18]). Try possible operations.
  |- Try 16 + 9 = 25. Add 25 to the number set. Current number set: [25, 6, 18], target: 12. Options for choosing two numbers: [(25, 6), (25, 18), (6, 18)].
   |- Pick two numbers (25, 6) (numbers left: [18]). Try possible operations.
    |- Try 25 + 6 = 31. Add 31 to the number set. Current number set: [31, 18], target: 12, just two numbers left.
     |- Try 31 + 18 = 49. Evaluate 49 != 12, drop this branch.
     |- Try 31 - 18 = 13. Evaluate 13 != 12, drop this branch.
     |- Try 31 * 18 = 558. Evaluate 558 != 12, drop this branch.
     |- Try 31 / 18 = 1.7. 1.7 is a decimal, drop this branch.
    |- Try 25 - 6 = 19. Add 19 to the number set. Current number set: [19, 18], target: 12, just two numbers left.
     |- Try 19 + 18 = 37. Evaluate 37 != 12, drop this branch.
     |- Try 19 - 18 = 1. Evaluate 1 != 12, drop this branch.
     |- Try 19 * 18 = 342. Evaluate 342 != 12, drop this branch.
     |- Try 19 / 18 = 1.1. 1.1 is a decimal, drop this branch.
    |- Try 25 * 6 = 150. Add 150 to the number set. Current number set: [150, 18], target: 12, just two numbers left.
     |- Try 150 + 18 = 168. Evaluate 168 != 12, drop this branch.
     |- Try 150 - 18 = 132. Evaluate 132 != 12, drop this branch.
     |- Try 150 * 18 = 2700. 2700 exceeds the maximum intermediate result, drop this branch.
     |- Try 150 / 18 = 8.3. 8.3 is a decimal, drop this branch.
    |- Try 25 / 6 = 4.2. 4.2 is a decimal, drop this branch.
   |- Pick two numbers (25, 18) (numbers left: [6]). Try possible operations.
    |- Try 25 + 18 = 43. Add 43 to the number set. Current number set: [43, 6], target: 12, just two numbers left.
     |- Try 43 + 6 = 49. Evaluate 49 != 12, drop this branch.
     |- Try 43 - 6 = 37. Evaluate 37 != 12, drop this branch.
     |- Try 43 * 6 = 258. Evaluate 258 != 12, drop this branch.
     |- Try 43 / 6 = 7.2. 7.2 is a decimal, drop this branch.
    |- Try 25 - 18 = 7. Add 7 to the number set. Current number set: [7, 6], target: 12, just two numbers left.
     |- Try 7 + 6 = 13. Evaluate 13 != 12, drop this branch.
     |- Try 7 - 6 = 1. Evaluate 1 != 12, drop this branch.
     |- Try 7 * 6 = 42. Evaluate 42 != 12, drop this branch.
     |- Try 7 / 6 = 1.2. 1.2 is a decimal, drop this branch.
    |- Try 25 * 18 = 450. Add 450 to the number set. Current number set: [450, 6], target: 12, just two numbers left.
     |- Try 450 + 6 = 456. Evaluate 456 != 12, drop this branch.
     |- Try 450 - 6 = 444. Evaluate 444 != 12, drop this branch.
     |- Try 450 * 6 = 2700. 2700 exceeds the maximum intermediate result, drop this branch.
     |- Try 450 / 6 = 75. Evaluate 75 != 12, drop this branch.
    |- Try 25 / 18 = 1.4. 1.4 is a decimal, drop this branch.
   |- Pick two numbers (6, 18) (numbers left: [25]). Try possible operations.
    |- Try 18 + 6 = 24. Add 24 to the number set. Current number set: [24, 25], target: 12, just two numbers left.
     |- Try 25 + 24 = 49. Evaluate 49 != 12, drop this branch.
     |- Try 25 - 24 = 1. Evaluate 1 != 12, drop this branch.
     |- Try 25 * 24 = 600. Evaluate 600 != 12, drop this branch.
     |- Try 25 / 24 = 1.0. 1.0 is a decimal, drop this branch.
    |- Try 18 - 6 = 12. Add 12 to the number set. Current number set: [12, 25], target: 12, just two numbers left.
     |- Try 25 + 12 = 37. Evaluate 37 != 12, drop this branch.
     |- Try 25 - 12 = 13. Evaluate 13 != 12, drop this branch.
     |- Try 25 * 12 = 300. Evaluate 300 != 12, drop this branch.
     |- Try 25 / 12 = 2.1. 2.1 is a decimal, drop this branch.
    |- Try 18 * 6 = 108. Add 108 to the number set. Current number set: [108, 25], target: 12, just two numbers left.
     |- Try 108 + 25 = 133. Evaluate 133 != 12, drop this branch.
     |- Try 108 - 25 = 83. Evaluate 83 != 12, drop this branch.
     |- Try 108 * 25 = 2700. 2700 exceeds the maximum intermediate result, drop this branch.
     |- Try 108 / 25 = 4.3. 4.3 is a decimal, drop this branch.
    |- Try 18 / 6 = 3. Add 3 to the number set. Current number set: [3, 25], target: 12, just two numbers left.
     |- Try 25 + 3 = 28. Evaluate 28 != 12, drop this branch.
     |- Try 25 - 3 = 22. Evaluate 22 != 12, drop this branch.
     |- Try 25 * 3 = 75. Evaluate 75 != 12, drop this branch.
     |- Try 25 / 3 = 8.3. 8.3 is a decimal, drop this branch.
  |- Try 16 - 9 = 7. Add 7 to the number set. Current number set: [7, 6, 18], target: 12. Options for choosing two numbers: [(7, 6), (7, 18), (6, 18)].
   |- Pick two numbers (7, 6) (numbers left: [18]). Try possible operations.
    |- Try 7 + 6 = 13. Add 13 to the number set. Current number set: [13, 18], target: 12, just two numbers left.
     |- Try 18 + 13 = 31. Evaluate 31 != 12, drop this branch.
     |- Try 18 - 13 = 5. Evaluate 5 != 12, drop this branch.
     |- Try 18 * 13 = 234. Evaluate 234 != 12, drop this branch.
     |- Try 18 / 13 = 1.4. 1.4 is a decimal, drop this branch.
    |- Try 7 - 6 = 1. Add 1 to the number set. Current number set: [1, 18], target: 12, just two numbers left.
     |- Try 18 + 1 = 19. Evaluate 19 != 12, drop this branch.
     |- Try 18 - 1 = 17. Evaluate 17 != 12, drop this branch.
     |- Try 18 * 1 = 18. Evaluate 18 != 12, drop this branch.
     |- Try 18 / 1 = 18. Evaluate 18 != 12, drop this branch.
    |- Try 7 * 6 = 42. Add 42 to the number set. Current number set: [42, 18], target: 12, just two numbers left.
     |- Try 42 + 18 = 60. Evaluate 60 != 12, drop this branch.
     |- Try 42 - 18 = 24. Evaluate 24 != 12, drop this branch.
     |- Try 42 * 18 = 756. Evaluate 756 != 12, drop this branch.
     |- Try 42 / 18 = 2.3. 2.3 is a decimal, drop this branch.
    |- Try 7 / 6 = 1.2. 1.2 is a decimal, drop this branch.
   |- Pick two numbers (7, 18) (numbers left: [6]). Try possible operations.
    |- Try 18 + 7 = 25. Add 25 to the number set. Current number set: [25, 6], target: 12, just two numbers left.
     |- Try 25 + 6 = 31. Evaluate 31 != 12, drop this branch.
     |- Try 25 - 6 = 19. Evaluate 19 != 12, drop this branch.
     |- Try 25 * 6 = 150. Evaluate 150 != 12, drop this branch.
     |- Try 25 / 6 = 4.2. 4.2 is a decimal, drop this branch.
    |- Try 18 - 7 = 11. Add 11 to the number set. Current number set: [11, 6], target: 12, just two numbers left.
     |- Try 11 + 6 = 17. Evaluate 17 != 12, drop this branch.
     |- Try 11 - 6 = 5. Evaluate 5 != 12, drop this branch.
     |- Try 11 * 6 = 66. Evaluate 66 != 12, drop this branch.
     |- Try 11 / 6 = 1.8. 1.8 is a decimal, drop this branch.
    |- Try 18 * 7 = 126. Add 126 to the number set. Current number set: [126, 6], target: 12, just two numbers left.
     |- Try 126 + 6 = 132. Evaluate 132 != 12, drop this branch.
     |- Try 126 - 6 = 120. Evaluate 120 != 12, drop this branch.
     |- Try 126 * 6 = 756. Evaluate 756 != 12, drop this branch.
     |- Try 126 / 6 = 21. Evaluate 21 != 12, drop this branch.
    |- Try 18 / 7 = 2.6. 2.6 is a decimal, drop this branch.
   |- Pick two numbers (6, 18) (numbers left: [7]). Try possible operations.
    |- Try 18 + 6 = 24. Add 24 to the number set. Current number set: [24, 7], target: 12, just two numbers left.
     |- Try 24 + 7 = 31. Evaluate 31 != 12, drop this branch.
     |- Try 24 - 7 = 17. Evaluate 17 != 12, drop this branch.
     |- Try 24 * 7 = 168. Evaluate 168 != 12, drop this branch.
     |- Try 24 / 7 = 3.4. 3.4 is a decimal, drop this branch.
    |- Try 18 - 6 = 12. Add 12 to the number set. Current number set: [12, 7], target: 12, just two numbers left.
     |- Try 12 + 7 = 19. Evaluate 19 != 12, drop this branch.
     |- Try 12 - 7 = 5. Evaluate 5 != 12, drop this branch.
     |- Try 12 * 7 = 84. Evaluate 84 != 12, drop this branch.
     |- Try 12 / 7 = 1.7. 1.7 is a decimal, drop this branch.
    |- Try 18 * 6 = 108. Add 108 to the number set. Current number set: [108, 7], target: 12, just two numbers left.
     |- Try 108 + 7 = 115. Evaluate 115 != 12, drop this branch.
     |- Try 108 - 7 = 101. Evaluate 101 != 12, drop this branch.
     |- Try 108 * 7 = 756. Evaluate 756 != 12, drop this branch.
     |- Try 108 / 7 = 15.4. 15.4 is a decimal, drop this branch.
    |- Try 18 / 6 = 3. Add 3 to the number set. Current number set: [3, 7], target: 12, just two numbers left.
     |- Try 7 + 3 = 10. Evaluate 10 != 12, drop this branch.
     |- Try 7 - 3 = 4. Evaluate 4 != 12, drop this branch.
     |- Try 7 * 3 = 21. Evaluate 21 != 12, drop this branch.
     |- Try 7 / 3 = 2.3. 2.3 is a decimal, drop this branch.
  |- Try 16 * 9 = 144. Add 144 to the number set. Current number set: [144, 6, 18], target: 12. Options for choosing two numbers: [(144, 6), (144, 18), (6, 18)].
   |- Pick two numbers (144, 6) (numbers left: [18]). Try possible operations.
    |- Try 144 + 6 = 150. Add 150 to the number set. Current number set: [150, 18], target: 12, just two numbers left.
     |- Try 150 + 18 = 168. Evaluate 168 != 12, drop this branch.
     |- Try 150 - 18 = 132. Evaluate 132 != 12, drop this branch.
     |- Try 150 * 18 = 2700. 2700 exceeds the maximum intermediate result, drop this branch.
     |- Try 150 / 18 = 8.3. 8.3 is a decimal, drop this branch.
    |- Try 144 - 6 = 138. Add 138 to the number set. Current number set: [138, 18], target: 12, just two numbers left.
     |- Try 138 + 18 = 156. Evaluate 156 != 12, drop this branch.
     |- Try 138 - 18 = 120. Evaluate 120 != 12, drop this branch.
     |- Try 138 * 18 = 2484. 2484 exceeds the maximum intermediate result, drop this branch.
     |- Try 138 / 18 = 7.7. 7.7 is a decimal, drop this branch.
    |- Try 144 * 6 = 864. Add 864 to the number set. Current number set: [864, 18], target: 12, just two numbers left.
     |- Try 864 + 18 = 882. Evaluate 882 != 12, drop this branch.
     |- Try 864 - 18 = 846. Evaluate 846 != 12, drop this branch.
     |- Try 864 * 18 = 15552. 15552 exceeds the maximum intermediate result, drop this branch.
     |- Try 864 / 18 = 48. Evaluate 48 != 12, drop this branch.
    |- Try 144 / 6 = 24. Add 24 to the number set. Current number set: [24, 18], target: 12, just two numbers left.
     |- Try 24 + 18 = 42. Evaluate 42 != 12, drop this branch.
     |- Try 24 - 18 = 6. Evaluate 6 != 12, drop this branch.
     |- Try 24 * 18 = 432. Evaluate 432 != 12, drop this branch.
     |- Try 24 / 18 = 1.3. 1.3 is a decimal, drop this branch.
   |- Pick two numbers (144, 18) (numbers left: [6]). Try possible operations.
    |- Try 144 + 18 = 162. Add 162 to the number set. Current number set: [162, 6], target: 12, just two numbers left.
     |- Try 162 + 6 = 168. Evaluate 168 != 12, drop this branch.
     |- Try 162 - 6 = 156. Evaluate 156 != 12, drop this branch.
     |- Try 162 * 6 = 972. Evaluate 972 != 12, drop this branch.
     |- Try 162 / 6 = 27. Evaluate 27 != 12, drop this branch.
    |- Try 144 - 18 = 126. Add 126 to the number set. Current number set: [126, 6], target: 12, just two numbers left.
     |- Try 126 + 6 = 132. Evaluate 132 != 12, drop this branch.
     |- Try 126 - 6 = 120. Evaluate 120 != 12, drop this branch.
     |- Try 126 * 6 = 756. Evaluate 756 != 12, drop this branch.
     |- Try 126 / 6 = 21. Evaluate 21 != 12, drop this branch.
    |- Try 144 * 18 = 2592. 2592 exceeds the maximum intermediate result, drop this branch.
    |- Try 144 / 18 = 8. Add 8 to the number set. Current number set: [8, 6], target: 12, just two numbers left.
     |- Try 8 + 6 = 14. Evaluate 14 != 12, drop this branch.
     |- Try 8 - 6 = 2. Evaluate 2 != 12, drop this branch.
     |- Try 8 * 6 = 48. Evaluate 48 != 12, drop this branch.
     |- Try 8 / 6 = 1.3. 1.3 is a decimal, drop this branch.
   |- Pick two numbers (6, 18) (numbers left: [144]). Try possible operations.
    |- Try 18 + 6 = 24. Add 24 to the number set. Current number set: [24, 144], target: 12, just two numbers left.
     |- Try 144 + 24 = 168. Evaluate 168 != 12, drop this branch.
     |- Try 144 - 24 = 120. Evaluate 120 != 12, drop this branch.
     |- Try 144 * 24 = 3456. 3456 exceeds the maximum intermediate result, drop this branch.
     |- Try 144 / 24 = 6. Evaluate 6 != 12, drop this branch.
    |- Try 18 - 6 = 12. Add 12 to the number set. Current number set: [12, 144], target: 12, just two numbers left.
     |- Try 144 + 12 = 156. Evaluate 156 != 12, drop this branch.
     |- Try 144 - 12 = 132. Evaluate 132 != 12, drop this branch.
     |- Try 144 * 12 = 1728. Evaluate 1728 != 12, drop this branch.
     |- Try 144 / 12 = 12. Evaluate 12 == 12, target found!

Now we have found the target, let's trace back the solution:
Final step: 144 / 12 = 12
The step before: 18 - 6 = 12
The first step: 16 * 9 = 144

Output the solution in the required format:
<Solution>
16 * 9 = 144
18 - 6 = 12
144 / 12 = 12
</Solution>

[Problem]
Now, solve the following problem. Note that:
- Please carefully read the approach and examples provided above, and follow them to solve the problem.
- Please ALWAYS include your search procedure (after # Search Procedure). The search procedure should follow the format of the examples provided above.
- Please mark your answer with <Solution> and </Solution> tags. The solution should be a sequence of three equations exactly following the format of the examples above, with no additional text in between.

Numbers: [46, 42, 38, 19]
Target: 15

# Search Procedure
Initial number set: [46, 42, 38, 19], target: 15. Options for choosing two numbers: [(46, 42), (46, 38), (46, 19), (42, 38), (42, 19), (38, 19)].
 |- Pick two numbers (46, 42) (numbers left: [38, 19]). Try possible operations.
  |- Try 46 + 42 = 88. Add 88 to the number set. Current number set: [88, 38, 19], target: 15. Options for choosing two numbers: [(88, 38), (88, 19), (38, 19)].
   |- Pick two numbers (88, 38) (numbers left: [19]). Try possible operations.
    |- Try 88 + 38 = 126. Add 126 to the number set. Current number set: [126, 19], target: 15, just two numbers left.
     |- Try 126 + 19 = 145. Evaluate 145 != 15, drop this branch.
     |- Try 126 - 19 = 107. Evaluate 107 != 15, drop this branch.
     |- Try 126 * 19 = 2394. 2394 exceeds the maximum intermediate result, drop this branch.
     |- Try 126 / 19 = 6.6. 6.6 is a decimal, drop this branch.
    |- Try 88 - 38 = 50. Add 50 to the number set. Current number set: [50, 19], target: 15, just two numbers left.
     |- Try 50 + 19 = 69. Evaluate 69 != 15, drop this branch.
     |- Try 50 - 19 = 31. Evaluate 31 != 15, drop this branch.
     |- Try 50 * 19 = 950. Evaluate 950 != 15, drop this branch.
     |- Try 50 / 19 = 2.6. 2.6 is a decimal, drop this branch.
    |- Try 88 * 38 = 3344. 3344 exceeds the maximum intermediate result, drop this branch.
    |- Try 88 / 38 = 2.3. 2.3 is a decimal, drop this branch.
   |- Pick two numbers (88, 19) (numbers left: [38]). Try possible operations.
    |- Try 88 + 19 = 107. Add 107 to the number set. Current number set: [107, 38], target: 15, just two numbers left.
     |- Try 107 + 38 = 145. Evaluate 145 != 15, drop this branch.
     |- Try 107 - 38 = 69. Evaluate 69 != 15, drop this branch.
     |- Try 107 * 38 = 4066. 4066 exceeds the maximum intermediate result, drop this branch.
     |- Try 107 / 38 = 2.8. 2.8 is a decimal, drop this branch.
    |- Try 88 - 19 = 69. Add 69 to the number set. Current number set: [69, 38], target: 15, just two numbers left.
     |- Try 69 + 38 = 107. Evaluate 107 != 15, drop this branch.
     |- Try 69 - 38 = 31. Evaluate 31 != 15, drop this branch.
     |- Try 69 * 38 = 2622. 2622 exceeds the maximum intermediate result, drop this branch.
     |- Try 69 / 38 = 1.8. 1.8 is a decimal, drop this branch.
    |- Try 88 * 19 = 1672. Add 1672 to the number set. Current number set: [1672, 38], target: 15, just two numbers left.
     |- Try 1672 + 38 = 1710. Evaluate 1710 != 15, drop this branch.
     |- Try 1672 - 38 = 1634. Evaluate 1634 != 15, drop this branch.
     |- Try 1672 * 38 = 63536. 63536 exceeds the maximum intermediate result, drop this branch.
     |- Try 1672 / 38 = 44. Evaluate 44 != 15, drop this branch.
    |- Try 88 / 19 = 4.6. 4.6 is a decimal, drop this branch.
   |- Pick two numbers (38, 19) (numbers left: [88]). Try possible operations.
    |- Try 38 + 19 = 57. Add 57 to the number set. Current number set: [57, 88], target: 15, just two numbers left.
     |- Try 88 + 57 = 145. Evaluate 145 != 15, drop this branch.
     |- Try 88 - 57 = 31. Evaluate 31 != 15, drop this branch.
     |- Try 88 * 57 = 5016. 5016 exceeds the maximum intermediate result, drop this branch.
     |- Try 88 / 57 = 1.5. 1.5 is a decimal, drop this branch.
    |- Try 38 - 19 = 19. Add 19 to the number set. Current number set: [19, 88], target: 15, just two numbers left.
     |- Try 88 + 19 = 107. Evaluate 107 != 15, drop this branch.
     |- Try 88 - 19 = 69. Evaluate 69 != 15, drop this branch.
     |- Try 88 * 19 = 1672. Evaluate 1672 != 15, drop this branch.
     |- Try 88 / 19 = 4.6. 4.6 is a decimal, drop this branch.
    |- Try 38 * 19 = 722. Add 722 to the number set. Current number set: [722, 88], target: 15, just two numbers left.
     |- Try 722 + 88 = 810. Evaluate 810 != 15, drop this branch.
     |- Try 722 - 88 = 634. Evaluate 634 != 15, drop this branch.
     |- Try 722 * 88 = 63536. 63536 exceeds the maximum intermediate result, drop this branch.
     |- Try 722 / 88 = 8.2. 8.2 is a decimal, drop this branch.
    |- Try 38 / 19 = 2. Add 2 to the number set. Current number set: [2, 88], target: 15, just two numbers left.
     |- Try 88 + 2 = 90. Evaluate 90 != 15, drop this branch.
     |- Try 88 - 2 = 86. Evaluate 86 != 15, drop this branch.
     |- Try 88 * 2 = 176. Evaluate 176 != 15, drop this branch.
     |- Try 88 / 2 = 44. Evaluate 44 != 15, drop this branch.
  |- Try 46 - 42 = 4. Add 4 to the number set. Current number set: [4, 38, 19], target: 15. Options for choosing two numbers: [(4, 38), (4, 19), (38, 19)].
   |- Pick two numbers (4, 38) (numbers left: [19]). Try possible operations.
    |- Try 38 + 4 = 42. Add 42 to the number set. Current number set: [42, 19], target: 15, just two numbers left.
     |- Try 42 + 19 = 61. Evaluate 61 != 15, drop this branch.
     |- Try 42 - 19 = 23. Evaluate 23 != 15, drop this branch.
     |- Try 42 * 19 = 798. Evaluate 798 != 15, drop this branch.
     |- Try 42 / 19 = 2.2. 2.2 is a decimal, drop this branch.
    |- Try 38 - 4 = 34. Add 34 to the number set. Current number set: [34, 19], target: 15, just two numbers left.
     |- Try 34 + 19 = 53. Evaluate 53 != 15, drop this branch.
     |- Try 34 - 19 = 15. Evaluate 15 == 15, target found!

Now we have found the target, let's trace back the solution:
Final step: 34 - 19 = 15
The step before: 38 - 4 = 34
The first step: 46 - 42 = 4

Output the solution in the required format:
<Solution>
46 - 42 = 4
38 - 4 = 34
34 - 19 = 15
</Solution>

Solution:
46 - 42 = 4
38 - 4 = 34
34 - 19 = 15


[TASK]
You will be given four numbers and a target number, your task is to find a way to use all four numbers exactly once, along with the basic operations (+, -, *, /), to reach the target number.

[RULES]
- You can use each number exactly once.
- You can use the four basic operations (+, -, *, /).
- The intermediate results must be integers (no decimals allowed).
- The intermediate results must be positive.
- The intermediate results will not exceed 2000.

[APPROACH]
We will solve the problem by searching. Starting from a given set of four numbers, we will follow this search process:
- At each state, we will consider all possible number pairs (in order) from the current number set. Choose one pair and apply one of the four basic operations to them to obtain a new number.
  * If there are still numbers left, we will add the new number to the number set and continue the search.
  * If we have used all numbers, we will check if the new number is equal to the target number. If it is, we have found the solution. Otherwise, we will backtrack.
- Suppose the two numbers we choose are a and b (where a >= b). We will try the four options (a + b), (a - b), (a * b), (a / b) to obtain the new number. Remember to always use the larger number as the first operand.
- If the new number is a decimal, or exceeds the maximum intermediate result, we will discard this branch and backtrack.
- We will continue this process until we reach the target number with four numbers used or exhaust all possible combinations.

[EXAMPLES]
# Example
Numbers: [40, 19, 23, 7]
Target: 29

# Search Procedure
Initial number set: [40, 19, 23, 7], target: 29. Options for choosing two numbers: [(40, 19), (40, 23), (40, 7), (19, 23), (19, 7), (23, 7)].
 |- Pick two numbers (40, 19) (numbers left: [23, 7]). Try possible operations.
  |- Try 40 + 19 = 59. Add 59 to the number set. Current number set: [59, 23, 7], target: 29. Options for choosing two numbers: [(59, 23), (59, 7), (23, 7)].
   |- Pick two numbers (59, 23) (numbers left: [7]). Try possible operations.
    |- Try 59 + 23 = 82. Add 82 to the number set. Current number set: [82, 7], target: 29, just two numbers left.
     |- Try 82 + 7 = 89. Evaluate 89 != 29, drop this branch.
     |- Try 82 - 7 = 75. Evaluate 75 != 29, drop this branch.
     |- Try 82 * 7 = 574. Evaluate 574 != 29, drop this branch.
     |- Try 82 / 7 = 11.7. 11.7 is a decimal, drop this branch.
    |- Try 59 - 23 = 36. Add 36 to the number set. Current number set: [36, 7], target: 29, just two numbers left.
     |- Try 36 + 7 = 43. Evaluate 43 != 29, drop this branch.
     |- Try 36 - 7 = 29. Evaluate 29 == 29, target found!

Now we have found the target, let's trace back the solution:
Final step: 36 - 7 = 29
The step before: 59 - 23 = 36
The first step: 40 + 19 = 59

Output the solution in the required format:
<Solution>
40 + 19 = 59
59 - 23 = 36
36 - 7 = 29
</Solution>

# Example
Numbers: [9, 16, 6, 18]
Target: 12

# Search Procedure
Initial number set: [9, 16, 6, 18], target: 12. Options for choosing two numbers: [(9, 16), (9, 6), (9, 18), (16, 6), (16, 18), (6, 18)].
 |- Pick two numbers (9, 16) (numbers left: [6, 18]). Try possible operations.
  |- Try 16 + 9 = 25. Add 25 to the number set. Current number set: [25, 6, 18], target: 12. Options for choosing two numbers: [(25, 6), (25, 18), (6, 18)].
   |- Pick two numbers (25, 6) (numbers left: [18]). Try possible operations.
    |- Try 25 + 6 = 31. Add 31 to the number set. Current number set: [31, 18], target: 12, just two numbers left.
     |- Try 31 + 18 = 49. Evaluate 49 != 12, drop this branch.
     |- Try 31 - 18 = 13. Evaluate 13 != 12, drop this branch.
     |- Try 31 * 18 = 558. Evaluate 558 != 12, drop this branch.
     |- Try 31 / 18 = 1.7. 1.7 is a decimal, drop this branch.
    |- Try 25 - 6 = 19. Add 19 to the number set. Current number set: [19, 18], target: 12, just two numbers left.
     |- Try 19 + 18 = 37. Evaluate 37 != 12, drop this branch.
     |- Try 19 - 18 = 1. Evaluate 1 != 12, drop this branch.
     |- Try 19 * 18 = 342. Evaluate 342 != 12, drop this branch.
     |- Try 19 / 18 = 1.1. 1.1 is a decimal, drop this branch.
    |- Try 25 * 6 = 150. Add 150 to the number set. Current number set: [150, 18], target: 12, just two numbers left.
     |- Try 150 + 18 = 168. Evaluate 168 != 12, drop this branch.
     |- Try 150 - 18 = 132. Evaluate 132 != 12, drop this branch.
     |- Try 150 * 18 = 2700. 2700 exceeds the maximum intermediate result, drop this branch.
     |- Try 150 / 18 = 8.3. 8.3 is a decimal, drop this branch.
    |- Try 25 / 6 = 4.2. 4.2 is a decimal, drop this branch.
   |- Pick two numbers (25, 18) (numbers left: [6]). Try possible operations.
    |- Try 25 + 18 = 43. Add 43 to the number set. Current number set: [43, 6], target: 12, just two numbers left.
     |- Try 43 + 6 = 49. Evaluate 49 != 12, drop this branch.
     |- Try 43 - 6 = 37. Evaluate 37 != 12, drop this branch.
     |- Try 43 * 6 = 258. Evaluate 258 != 12, drop this branch.
     |- Try 43 / 6 = 7.2. 7.2 is a decimal, drop this branch.
    |- Try 25 - 18 = 7. Add 7 to the number set. Current number set: [7, 6], target: 12, just two numbers left.
     |- Try 7 + 6 = 13. Evaluate 13 != 12, drop this branch.
     |- Try 7 - 6 = 1. Evaluate 1 != 12, drop this branch.
     |- Try 7 * 6 = 42. Evaluate 42 != 12, drop this branch.
     |- Try 7 / 6 = 1.2. 1.2 is a decimal, drop this branch.
    |- Try 25 * 18 = 450. Add 450 to the number set. Current number set: [450, 6], target: 12, just two numbers left.
     |- Try 450 + 6 = 456. Evaluate 456 != 12, drop this branch.
     |- Try 450 - 6 = 444. Evaluate 444 != 12, drop this branch.
     |- Try 450 * 6 = 2700. 2700 exceeds the maximum intermediate result, drop this branch.
     |- Try 450 / 6 = 75. Evaluate 75 != 12, drop this branch.
    |- Try 25 / 18 = 1.4. 1.4 is a decimal, drop this branch.
   |- Pick two numbers (6, 18) (numbers left: [25]). Try possible operations.
    |- Try 18 + 6 = 24. Add 24 to the number set. Current number set: [24, 25], target: 12, just two numbers left.
     |- Try 25 + 24 = 49. Evaluate 49 != 12, drop this branch.
     |- Try 25 - 24 = 1. Evaluate 1 != 12, drop this branch.
     |- Try 25 * 24 = 600. Evaluate 600 != 12, drop this branch.
     |- Try 25 / 24 = 1.0. 1.0 is a decimal, drop this branch.
    |- Try 18 - 6 = 12. Add 12 to the number set. Current number set: [12, 25], target: 12, just two numbers left.
     |- Try 25 + 12 = 37. Evaluate 37 != 12, drop this branch.
     |- Try 25 - 12 = 13. Evaluate 13 != 12, drop this branch.
     |- Try 25 * 12 = 300. Evaluate 300 != 12, drop this branch.
     |- Try 25 / 12 = 2.1. 2.1 is a decimal, drop this branch.
    |- Try 18 * 6 = 108. Add 108 to the number set. Current number set: [108, 25], target: 12, just two numbers left.
     |- Try 108 + 25 = 133. Evaluate 133 != 12, drop this branch.
     |- Try 108 - 25 = 83. Evaluate 83 != 12, drop this branch.
     |- Try 108 * 25 = 2700. 2700 exceeds the maximum intermediate result, drop this branch.
     |- Try 108 / 25 = 4.3. 4.3 is a decimal, drop this branch.
    |- Try 18 / 6 = 3. Add 3 to the number set. Current number set: [3, 25], target: 12, just two numbers left.
     |- Try 25 + 3 = 28. Evaluate 28 != 12, drop this branch.
     |- Try 25 - 3 = 22. Evaluate 22 != 12, drop this branch.
     |- Try 25 * 3 = 75. Evaluate 75 != 12, drop this branch.
     |- Try 25 / 3 = 8.3. 8.3 is a decimal, drop this branch.
  |- Try 16 - 9 = 7. Add 7 to the number set. Current number set: [7, 6, 18], target: 12. Options for choosing two numbers: [(7, 6), (7, 18), (6, 18)].
   |- Pick two numbers (7, 6) (numbers left: [18]). Try possible operations.
    |- Try 7 + 6 = 13. Add 13 to the number set. Current number set: [13, 18], target: 12, just two numbers left.
     |- Try 18 + 13 = 31. Evaluate 31 != 12, drop this branch.
     |- Try 18 - 13 = 5. Evaluate 5 != 12, drop this branch.
     |- Try 18 * 13 = 234. Evaluate 234 != 12, drop this branch.
     |- Try 18 / 13 = 1.4. 1.4 is a decimal, drop this branch.
    |- Try 7 - 6 = 1. Add 1 to the number set. Current number set: [1, 18], target: 12, just two numbers left.
     |- Try 18 + 1 = 19. Evaluate 19 != 12, drop this branch.
     |- Try 18 - 1 = 17. Evaluate 17 != 12, drop this branch.
     |- Try 18 * 1 = 18. Evaluate 18 != 12, drop this branch.
     |- Try 18 / 1 = 18. Evaluate 18 != 12, drop this branch.
    |- Try 7 * 6 = 42. Add 42 to the number set. Current number set: [42, 18], target: 12, just two numbers left.
     |- Try 42 + 18 = 60. Evaluate 60 != 12, drop this branch.
     |- Try 42 - 18 = 24. Evaluate 24 != 12, drop this branch.
     |- Try 42 * 18 = 756. Evaluate 756 != 12, drop this branch.
     |- Try 42 / 18 = 2.3. 2.3 is a decimal, drop this branch.
    |- Try 7 / 6 = 1.2. 1.2 is a decimal, drop this branch.
   |- Pick two numbers (7, 18) (numbers left: [6]). Try possible operations.
    |- Try 18 + 7 = 25. Add 25 to the number set. Current number set: [25, 6], target: 12, just two numbers left.
     |- Try 25 + 6 = 31. Evaluate 31 != 12, drop this branch.
     |- Try 25 - 6 = 19. Evaluate 19 != 12, drop this branch.
     |- Try 25 * 6 = 150. Evaluate 150 != 12, drop this branch.
     |- Try 25 / 6 = 4.2. 4.2 is a decimal, drop this branch.
    |- Try 18 - 7 = 11. Add 11 to the number set. Current number set: [11, 6], target: 12, just two numbers left.
     |- Try 11 + 6 = 17. Evaluate 17 != 12, drop this branch.
     |- Try 11 - 6 = 5. Evaluate 5 != 12, drop this branch.
     |- Try 11 * 6 = 66. Evaluate 66 != 12, drop this branch.
     |- Try 11 / 6 = 1.8. 1.8 is a decimal, drop this branch.
    |- Try 18 * 7 = 126. Add 126 to the number set. Current number set: [126, 6], target: 12, just two numbers left.
     |- Try 126 + 6 = 132. Evaluate 132 != 12, drop this branch.
     |- Try 126 - 6 = 120. Evaluate 120 != 12, drop this branch.
     |- Try 126 * 6 = 756. Evaluate 756 != 12, drop this branch.
     |- Try 126 / 6 = 21. Evaluate 21 != 12, drop this branch.
    |- Try 18 / 7 = 2.6. 2.6 is a decimal, drop this branch.
   |- Pick two numbers (6, 18) (numbers left: [7]). Try possible operations.
    |- Try 18 + 6 = 24. Add 24 to the number set. Current number set: [24, 7], target: 12, just two numbers left.
     |- Try 24 + 7 = 31. Evaluate 31 != 12, drop this branch.
     |- Try 24 - 7 = 17. Evaluate 17 != 12, drop this branch.
     |- Try 24 * 7 = 168. Evaluate 168 != 12, drop this branch.
     |- Try 24 / 7 = 3.4. 3.4 is a decimal, drop this branch.
    |- Try 18 - 6 = 12. Add 12 to the number set. Current number set: [12, 7], target: 12, just two numbers left.
     |- Try 12 + 7 = 19. Evaluate 19 != 12, drop this branch.
     |- Try 12 - 7 = 5. Evaluate 5 != 12, drop this branch.
     |- Try 12 * 7 = 84. Evaluate 84 != 12, drop this branch.
     |- Try 12 / 7 = 1.7. 1.7 is a decimal, drop this branch.
    |- Try 18 * 6 = 108. Add 108 to the number set. Current number set: [108, 7], target: 12, just two numbers left.
     |- Try 108 + 7 = 115. Evaluate 115 != 12, drop this branch.
     |- Try 108 - 7 = 101. Evaluate 101 != 12, drop this branch.
     |- Try 108 * 7 = 756. Evaluate 756 != 12, drop this branch.
     |- Try 108 / 7 = 15.4. 15.4 is a decimal, drop this branch.
    |- Try 18 / 6 = 3. Add 3 to the number set. Current number set: [3, 7], target: 12, just two numbers left.
     |- Try 7 + 3 = 10. Evaluate 10 != 12, drop this branch.
     |- Try 7 - 3 = 4. Evaluate 4 != 12, drop this branch.
     |- Try 7 * 3 = 21. Evaluate 21 != 12, drop this branch.
     |- Try 7 / 3 = 2.3. 2.3 is a decimal, drop this branch.
  |- Try 16 * 9 = 144. Add 144 to the number set. Current number set: [144, 6, 18], target: 12. Options for choosing two numbers: [(144, 6), (144, 18), (6, 18)].
   |- Pick two numbers (144, 6) (numbers left: [18]). Try possible operations.
    |- Try 144 + 6 = 150. Add 150 to the number set. Current number set: [150, 18], target: 12, just two numbers left.
     |- Try 150 + 18 = 168. Evaluate 168 != 12, drop this branch.
     |- Try 150 - 18 = 132. Evaluate 132 != 12, drop this branch.
     |- Try 150 * 18 = 2700. 2700 exceeds the maximum intermediate result, drop this branch.
     |- Try 150 / 18 = 8.3. 8.3 is a decimal, drop this branch.
    |- Try 144 - 6 = 138. Add 138 to the number set. Current number set: [138, 18], target: 12, just two numbers left.
     |- Try 138 + 18 = 156. Evaluate 156 != 12, drop this branch.
     |- Try 138 - 18 = 120. Evaluate 120 != 12, drop this branch.
     |- Try 138 * 18 = 2484. 2484 exceeds the maximum intermediate result, drop this branch.
     |- Try 138 / 18 = 7.7. 7.7 is a decimal, drop this branch.
    |- Try 144 * 6 = 864. Add 864 to the number set. Current number set: [864, 18], target: 12, just two numbers left.
     |- Try 864 + 18 = 882. Evaluate 882 != 12, drop this branch.
     |- Try 864 - 18 = 846. Evaluate 846 != 12, drop this branch.
     |- Try 864 * 18 = 15552. 15552 exceeds the maximum intermediate result, drop this branch.
     |- Try 864 / 18 = 48. Evaluate 48 != 12, drop this branch.
    |- Try 144 / 6 = 24. Add 24 to the number set. Current number set: [24, 18], target: 12, just two numbers left.
     |- Try 24 + 18 = 42. Evaluate 42 != 12, drop this branch.
     |- Try 24 - 18 = 6. Evaluate 6 != 12, drop this branch.
     |- Try 24 * 18 = 432. Evaluate 432 != 12, drop this branch.
     |- Try 24 / 18 = 1.3. 1.3 is a decimal, drop this branch.
   |- Pick two numbers (144, 18) (numbers left: [6]). Try possible operations.
    |- Try 144 + 18 = 162. Add 162 to the number set. Current number set: [162, 6], target: 12, just two numbers left.
     |- Try 162 + 6 = 168. Evaluate 168 != 12, drop this branch.
     |- Try 162 - 6 = 156. Evaluate 156 != 12, drop this branch.
     |- Try 162 * 6 = 972. Evaluate 972 != 12, drop this branch.
     |- Try 162 / 6 = 27. Evaluate 27 != 12, drop this branch.
    |- Try 144 - 18 = 126. Add 126 to the number set. Current number set: [126, 6], target: 12, just two numbers left.
     |- Try 126 + 6 = 132. Evaluate 132 != 12, drop this branch.
     |- Try 126 - 6 = 120. Evaluate 120 != 12, drop this branch.
     |- Try 126 * 6 = 756. Evaluate 756 != 12, drop this branch.
     |- Try 126 / 6 = 21. Evaluate 21 != 12, drop this branch.
    |- Try 144 * 18 = 2592. 2592 exceeds the maximum intermediate result, drop this branch.
    |- Try 144 / 18 = 8. Add 8 to the number set. Current number set: [8, 6], target: 12, just two numbers left.
     |- Try 8 + 6 = 14. Evaluate 14 != 12, drop this branch.
     |- Try 8 - 6 = 2. Evaluate 2 != 12, drop this branch.
     |- Try 8 * 6 = 48. Evaluate 48 != 12, drop this branch.
     |- Try 8 / 6 = 1.3. 1.3 is a decimal, drop this branch.
   |- Pick two numbers (6, 18) (numbers left: [144]). Try possible operations.
    |- Try 18 + 6 = 24. Add 24 to the number set. Current number set: [24, 144], target: 12, just two numbers left.
     |- Try 144 + 24 = 168. Evaluate 168 != 12, drop this branch.
     |- Try 144 - 24 = 120. Evaluate 120 != 12, drop this branch.
     |- Try 144 * 24 = 3456. 3456 exceeds the maximum intermediate result, drop this branch.
     |- Try 144 / 24 = 6. Evaluate 6 != 12, drop this branch.
    |- Try 18 - 6 = 12. Add 12 to the number set. Current number set: [12, 144], target: 12, just two numbers left.
     |- Try 144 + 12 = 156. Evaluate 156 != 12, drop this branch.
     |- Try 144 - 12 = 132. Evaluate 132 != 12, drop this branch.
     |- Try 144 * 12 = 1728. Evaluate 1728 != 12, drop this branch.
     |- Try 144 / 12 = 12. Evaluate 12 == 12, target found!

Now we have found the target, let's trace back the solution:
Final step: 144 / 12 = 12
The step before: 18 - 6 = 12
The first step: 16 * 9 = 144

Output the solution in the required format:
<Solution>
16 * 9 = 144
18 - 6 = 12
144 / 12 = 12
</Solution>

[Problem]
Now, solve the following problem. Note that:
- Please carefully read the approach and examples provided above, and follow them to solve the problem.
- Please ALWAYS include your search procedure (after # Search Procedure). The search procedure should follow the format of the examples provided above.
- Please mark your answer with <Solution> and </Solution> tags. The solution should be a sequence of three equations exactly following the format of the examples above, with no additional text in between.

Numbers: [42, 24, 19, 14]
Target: 13

# Search Procedure
Initial number set: [42, 24, 19, 14], target: 13. Options for choosing two numbers: [(42, 24), (42, 19), (42, 14), (24, 19), (24, 14), (19, 14)].
 |- Pick two numbers (42, 24) (numbers left: [19, 14]). Try possible operations.
  |- Try 42 + 24 = 66. Add 66 to the number set. Current number set: [66, 19, 14], target: 13. Options for choosing two numbers: [(66, 19), (66, 14), (19, 14)].
   |- Pick two numbers (66, 19) (numbers left: [14]). Try possible operations.
    |- Try 66 + 19 = 85. Add 85 to the number set. Current number set: [85, 14], target: 13, just two numbers left.
     |- Try 85 + 14 = 99. Evaluate 99 != 13, drop this branch.
     |- Try 85 - 14 = 71. Evaluate 71 != 13, drop this branch.
     |- Try 85 * 14 = 1190. Evaluate 1190 != 13, drop this branch.
     |- Try 85 / 14 = 6.1. 6.1 is a decimal, drop this branch.
    |- Try 66 - 19 = 47. Add 47 to the number set. Current number set: [47, 14], target: 13, just two numbers left.
     |- Try 47 + 14 = 61. Evaluate 61 != 13, drop this branch.
     |- Try 47 - 14 = 33. Evaluate 33 != 13, drop this branch.
     |- Try 47 * 14 = 658. Evaluate 658 != 13, drop this branch.
     |- Try 47 / 14 = 3.4. 3.4 is a decimal, drop this branch.
    |- Try 66 * 19 = 1254. Add 1254 to the number set. Current number set: [1254, 14], target: 13, just two numbers left.
     |- Try 1254 + 14 = 1268. Evaluate 1268 != 13, drop this branch.
     |- Try 1254 - 14 = 1240. Evaluate 1240 != 13, drop this branch.
     |- Try 1254 * 14 = 17556. 17556 exceeds the maximum intermediate result, drop this branch.
     |- Try 1254 / 14 = 89.6. 89.6 is a decimal, drop this branch.
    |- Try 66 / 19 = 3.5. 3.5 is a decimal, drop this branch.
   |- Pick two numbers (66, 14) (numbers left: [19]). Try possible operations.
    |- Try 66 + 14 = 80. Add 80 to the number set. Current number set: [80, 19], target: 13, just two numbers left.
     |- Try 80 + 19 = 99. Evaluate 99 != 13, drop this branch.
     |- Try 80 - 19 = 61. Evaluate 61 != 13, drop this branch.
     |- Try 80 * 19 = 1520. Evaluate 1520 != 13, drop this branch.
     |- Try 80 / 19 = 4.2. 4.2 is a decimal, drop this branch.
    |- Try 66 - 14 = 52. Add 52 to the number set. Current number set: [52, 19], target: 13, just two numbers left.
     |- Try 52 + 19 = 71. Evaluate 71 != 13, drop this branch.
     |- Try 52 - 19 = 33. Evaluate 33 != 13, drop this branch.
     |- Try 52 * 19 = 988. Evaluate 988 != 13, drop this branch.
     |- Try 52 / 19 = 2.7. 2.7 is a decimal, drop this branch.
    |- Try 66 * 14 = 924. Add 924 to the number set. Current number set: [924, 19], target: 13, just two numbers left.
     |- Try 924 + 19 = 943. Evaluate 943 != 13, drop this branch.
     |- Try 924 - 19 = 905. Evaluate 905 != 13, drop this branch.
     |- Try 924 * 19 = 17556. 17556 exceeds the maximum intermediate result, drop this branch.
     |- Try 924 / 19 = 48.6. 48.6 is a decimal, drop this branch.
    |- Try 66 / 14 = 4.7. 4.7 is a decimal, drop this branch.
   |- Pick two numbers (19, 14) (numbers left: [66]). Try possible operations.
    |- Try 19 + 14 = 33. Add 33 to the number set. Current number set: [33, 66], target: 13, just two numbers left.
     |- Try 66 + 33 = 99. Evaluate 99 != 13, drop this branch.
     |- Try 66 - 33 = 33. Evaluate 33 != 13, drop this branch.
     |- Try 66 * 33 = 2178. 2178 exceeds the maximum intermediate result, drop this branch.
     |- Try 66 / 33 = 2. Evaluate 2 != 13, drop this branch.
    |- Try 19 - 14 = 5. Add 5 to the number set. Current number set: [5, 66], target: 13, just two numbers left.
     |- Try 66 + 5 = 71. Evaluate 71 != 13, drop this branch.
     |- Try 66 - 5 = 61. Evaluate 61 != 13, drop this branch.
     |- Try 66 * 5 = 330. Evaluate 330 != 13, drop this branch.
     |- Try 66 / 5 = 13.2. 13.2 is a decimal, drop this branch.
    |- Try 19 * 14 = 266. Add 266 to the number set. Current number set: [266, 66], target: 13, just two numbers left.
     |- Try 266 + 66 = 332. Evaluate 332 != 13, drop this branch.
     |- Try 266 - 66 = 200. Evaluate 200 != 13, drop this branch.
     |- Try 266 * 66 = 17556. 17556 exceeds the maximum intermediate result, drop this branch.
     |- Try 266 / 66 = 4.0. 4.0 is a decimal, drop this branch.
    |- Try 19 / 14 = 1.4. 1.4 is a decimal, drop this branch.
  |- Try 42 - 24 = 18. Add 18 to the number set. Current number set: [18, 19, 14], target: 13. Options for choosing two numbers: [(18, 19), (18, 14), (19, 14)].
   |- Pick two numbers (18, 19) (numbers left: [14]). Try possible operations.
    |- Try 19 + 18 = 37. Add 37 to the number set. Current number set: [37, 14], target: 13, just two numbers left.
     |- Try 37 + 14 = 51. Evaluate 51 != 13, drop this branch.
     |- Try 37 - 14 = 23. Evaluate 23 != 13, drop this branch.
     |- Try 37 * 14 = 518. Evaluate 518 != 13, drop this branch.
     |- Try 37 / 14 = 2.6. 2.6 is a decimal, drop this branch.
    |- Try 19 - 18 = 1. Add 1 to the number set. Current number set: [1, 14], target: 13, just two numbers left.
     |- Try 14 + 1 = 15. Evaluate 15 != 13, drop this branch.
     |- Try 14 - 1 = 13. Evaluate 13 == 13, target found!

Now we have found the target, let's trace back the solution:
Final step: 14 - 1 = 13
The step before: 19 - 18 = 1
The first step: 42 - 24 = 18

Output the solution in the required format:
<Solution>
42 - 24 = 18
19 - 18 = 1
14 - 1 = 13
</Solution>

Solution:
42 - 24 = 18
19 - 18 = 1
14 - 1 = 13


[TASK]
You will be given four numbers and a target number, your task is to find a way to use all four numbers exactly once, along with the basic operations (+, -, *, /), to reach the target number.

[RULES]
- You can use each number exactly once.
- You can use the four basic operations (+, -, *, /).
- The intermediate results must be integers (no decimals allowed).
- The intermediate results must be positive.
- The intermediate results will not exceed 2000.

[APPROACH]
We will solve the problem by searching. Starting from a given set of four numbers, we will follow this search process:
- At each state, we will consider all possible number pairs (in order) from the current number set. Choose one pair and apply one of the four basic operations to them to obtain a new number.
  * If there are still numbers left, we will add the new number to the number set and continue the search.
  * If we have used all numbers, we will check if the new number is equal to the target number. If it is, we have found the solution. Otherwise, we will backtrack.
- Suppose the two numbers we choose are a and b (where a >= b). We will try the four options (a + b), (a - b), (a * b), (a / b) to obtain the new number. Remember to always use the larger number as the first operand.
- If the new number is a decimal, or exceeds the maximum intermediate result, we will discard this branch and backtrack.
- We will continue this process until we reach the target number with four numbers used or exhaust all possible combinations.

[EXAMPLES]
# Example
Numbers: [40, 19, 23, 7]
Target: 29

# Search Procedure
Initial number set: [40, 19, 23, 7], target: 29. Options for choosing two numbers: [(40, 19), (40, 23), (40, 7), (19, 23), (19, 7), (23, 7)].
 |- Pick two numbers (40, 19) (numbers left: [23, 7]). Try possible operations.
  |- Try 40 + 19 = 59. Add 59 to the number set. Current number set: [59, 23, 7], target: 29. Options for choosing two numbers: [(59, 23), (59, 7), (23, 7)].
   |- Pick two numbers (59, 23) (numbers left: [7]). Try possible operations.
    |- Try 59 + 23 = 82. Add 82 to the number set. Current number set: [82, 7], target: 29, just two numbers left.
     |- Try 82 + 7 = 89. Evaluate 89 != 29, drop this branch.
     |- Try 82 - 7 = 75. Evaluate 75 != 29, drop this branch.
     |- Try 82 * 7 = 574. Evaluate 574 != 29, drop this branch.
     |- Try 82 / 7 = 11.7. 11.7 is a decimal, drop this branch.
    |- Try 59 - 23 = 36. Add 36 to the number set. Current number set: [36, 7], target: 29, just two numbers left.
     |- Try 36 + 7 = 43. Evaluate 43 != 29, drop this branch.
     |- Try 36 - 7 = 29. Evaluate 29 == 29, target found!

Now we have found the target, let's trace back the solution:
Final step: 36 - 7 = 29
The step before: 59 - 23 = 36
The first step: 40 + 19 = 59

Output the solution in the required format:
<Solution>
40 + 19 = 59
59 - 23 = 36
36 - 7 = 29
</Solution>

# Example
Numbers: [9, 16, 6, 18]
Target: 12

# Search Procedure
Initial number set: [9, 16, 6, 18], target: 12. Options for choosing two numbers: [(9, 16), (9, 6), (9, 18), (16, 6), (16, 18), (6, 18)].
 |- Pick two numbers (9, 16) (numbers left: [6, 18]). Try possible operations.
  |- Try 16 + 9 = 25. Add 25 to the number set. Current number set: [25, 6, 18], target: 12. Options for choosing two numbers: [(25, 6), (25, 18), (6, 18)].
   |- Pick two numbers (25, 6) (numbers left: [18]). Try possible operations.
    |- Try 25 + 6 = 31. Add 31 to the number set. Current number set: [31, 18], target: 12, just two numbers left.
     |- Try 31 + 18 = 49. Evaluate 49 != 12, drop this branch.
     |- Try 31 - 18 = 13. Evaluate 13 != 12, drop this branch.
     |- Try 31 * 18 = 558. Evaluate 558 != 12, drop this branch.
     |- Try 31 / 18 = 1.7. 1.7 is a decimal, drop this branch.
    |- Try 25 - 6 = 19. Add 19 to the number set. Current number set: [19, 18], target: 12, just two numbers left.
     |- Try 19 + 18 = 37. Evaluate 37 != 12, drop this branch.
     |- Try 19 - 18 = 1. Evaluate 1 != 12, drop this branch.
     |- Try 19 * 18 = 342. Evaluate 342 != 12, drop this branch.
     |- Try 19 / 18 = 1.1. 1.1 is a decimal, drop this branch.
    |- Try 25 * 6 = 150. Add 150 to the number set. Current number set: [150, 18], target: 12, just two numbers left.
     |- Try 150 + 18 = 168. Evaluate 168 != 12, drop this branch.
     |- Try 150 - 18 = 132. Evaluate 132 != 12, drop this branch.
     |- Try 150 * 18 = 2700. 2700 exceeds the maximum intermediate result, drop this branch.
     |- Try 150 / 18 = 8.3. 8.3 is a decimal, drop this branch.
    |- Try 25 / 6 = 4.2. 4.2 is a decimal, drop this branch.
   |- Pick two numbers (25, 18) (numbers left: [6]). Try possible operations.
    |- Try 25 + 18 = 43. Add 43 to the number set. Current number set: [43, 6], target: 12, just two numbers left.
     |- Try 43 + 6 = 49. Evaluate 49 != 12, drop this branch.
     |- Try 43 - 6 = 37. Evaluate 37 != 12, drop this branch.
     |- Try 43 * 6 = 258. Evaluate 258 != 12, drop this branch.
     |- Try 43 / 6 = 7.2. 7.2 is a decimal, drop this branch.
    |- Try 25 - 18 = 7. Add 7 to the number set. Current number set: [7, 6], target: 12, just two numbers left.
     |- Try 7 + 6 = 13. Evaluate 13 != 12, drop this branch.
     |- Try 7 - 6 = 1. Evaluate 1 != 12, drop this branch.
     |- Try 7 * 6 = 42. Evaluate 42 != 12, drop this branch.
     |- Try 7 / 6 = 1.2. 1.2 is a decimal, drop this branch.
    |- Try 25 * 18 = 450. Add 450 to the number set. Current number set: [450, 6], target: 12, just two numbers left.
     |- Try 450 + 6 = 456. Evaluate 456 != 12, drop this branch.
     |- Try 450 - 6 = 444. Evaluate 444 != 12, drop this branch.
     |- Try 450 * 6 = 2700. 2700 exceeds the maximum intermediate result, drop this branch.
     |- Try 450 / 6 = 75. Evaluate 75 != 12, drop this branch.
    |- Try 25 / 18 = 1.4. 1.4 is a decimal, drop this branch.
   |- Pick two numbers (6, 18) (numbers left: [25]). Try possible operations.
    |- Try 18 + 6 = 24. Add 24 to the number set. Current number set: [24, 25], target: 12, just two numbers left.
     |- Try 25 + 24 = 49. Evaluate 49 != 12, drop this branch.
     |- Try 25 - 24 = 1. Evaluate 1 != 12, drop this branch.
     |- Try 25 * 24 = 600. Evaluate 600 != 12, drop this branch.
     |- Try 25 / 24 = 1.0. 1.0 is a decimal, drop this branch.
    |- Try 18 - 6 = 12. Add 12 to the number set. Current number set: [12, 25], target: 12, just two numbers left.
     |- Try 25 + 12 = 37. Evaluate 37 != 12, drop this branch.
     |- Try 25 - 12 = 13. Evaluate 13 != 12, drop this branch.
     |- Try 25 * 12 = 300. Evaluate 300 != 12, drop this branch.
     |- Try 25 / 12 = 2.1. 2.1 is a decimal, drop this branch.
    |- Try 18 * 6 = 108. Add 108 to the number set. Current number set: [108, 25], target: 12, just two numbers left.
     |- Try 108 + 25 = 133. Evaluate 133 != 12, drop this branch.
     |- Try 108 - 25 = 83. Evaluate 83 != 12, drop this branch.
     |- Try 108 * 25 = 2700. 2700 exceeds the maximum intermediate result, drop this branch.
     |- Try 108 / 25 = 4.3. 4.3 is a decimal, drop this branch.
    |- Try 18 / 6 = 3. Add 3 to the number set. Current number set: [3, 25], target: 12, just two numbers left.
     |- Try 25 + 3 = 28. Evaluate 28 != 12, drop this branch.
     |- Try 25 - 3 = 22. Evaluate 22 != 12, drop this branch.
     |- Try 25 * 3 = 75. Evaluate 75 != 12, drop this branch.
     |- Try 25 / 3 = 8.3. 8.3 is a decimal, drop this branch.
  |- Try 16 - 9 = 7. Add 7 to the number set. Current number set: [7, 6, 18], target: 12. Options for choosing two numbers: [(7, 6), (7, 18), (6, 18)].
   |- Pick two numbers (7, 6) (numbers left: [18]). Try possible operations.
    |- Try 7 + 6 = 13. Add 13 to the number set. Current number set: [13, 18], target: 12, just two numbers left.
     |- Try 18 + 13 = 31. Evaluate 31 != 12, drop this branch.
     |- Try 18 - 13 = 5. Evaluate 5 != 12, drop this branch.
     |- Try 18 * 13 = 234. Evaluate 234 != 12, drop this branch.
     |- Try 18 / 13 = 1.4. 1.4 is a decimal, drop this branch.
    |- Try 7 - 6 = 1. Add 1 to the number set. Current number set: [1, 18], target: 12, just two numbers left.
     |- Try 18 + 1 = 19. Evaluate 19 != 12, drop this branch.
     |- Try 18 - 1 = 17. Evaluate 17 != 12, drop this branch.
     |- Try 18 * 1 = 18. Evaluate 18 != 12, drop this branch.
     |- Try 18 / 1 = 18. Evaluate 18 != 12, drop this branch.
    |- Try 7 * 6 = 42. Add 42 to the number set. Current number set: [42, 18], target: 12, just two numbers left.
     |- Try 42 + 18 = 60. Evaluate 60 != 12, drop this branch.
     |- Try 42 - 18 = 24. Evaluate 24 != 12, drop this branch.
     |- Try 42 * 18 = 756. Evaluate 756 != 12, drop this branch.
     |- Try 42 / 18 = 2.3. 2.3 is a decimal, drop this branch.
    |- Try 7 / 6 = 1.2. 1.2 is a decimal, drop this branch.
   |- Pick two numbers (7, 18) (numbers left: [6]). Try possible operations.
    |- Try 18 + 7 = 25. Add 25 to the number set. Current number set: [25, 6], target: 12, just two numbers left.
     |- Try 25 + 6 = 31. Evaluate 31 != 12, drop this branch.
     |- Try 25 - 6 = 19. Evaluate 19 != 12, drop this branch.
     |- Try 25 * 6 = 150. Evaluate 150 != 12, drop this branch.
     |- Try 25 / 6 = 4.2. 4.2 is a decimal, drop this branch.
    |- Try 18 - 7 = 11. Add 11 to the number set. Current number set: [11, 6], target: 12, just two numbers left.
     |- Try 11 + 6 = 17. Evaluate 17 != 12, drop this branch.
     |- Try 11 - 6 = 5. Evaluate 5 != 12, drop this branch.
     |- Try 11 * 6 = 66. Evaluate 66 != 12, drop this branch.
     |- Try 11 / 6 = 1.8. 1.8 is a decimal, drop this branch.
    |- Try 18 * 7 = 126. Add 126 to the number set. Current number set: [126, 6], target: 12, just two numbers left.
     |- Try 126 + 6 = 132. Evaluate 132 != 12, drop this branch.
     |- Try 126 - 6 = 120. Evaluate 120 != 12, drop this branch.
     |- Try 126 * 6 = 756. Evaluate 756 != 12, drop this branch.
     |- Try 126 / 6 = 21. Evaluate 21 != 12, drop this branch.
    |- Try 18 / 7 = 2.6. 2.6 is a decimal, drop this branch.
   |- Pick two numbers (6, 18) (numbers left: [7]). Try possible operations.
    |- Try 18 + 6 = 24. Add 24 to the number set. Current number set: [24, 7], target: 12, just two numbers left.
     |- Try 24 + 7 = 31. Evaluate 31 != 12, drop this branch.
     |- Try 24 - 7 = 17. Evaluate 17 != 12, drop this branch.
     |- Try 24 * 7 = 168. Evaluate 168 != 12, drop this branch.
     |- Try 24 / 7 = 3.4. 3.4 is a decimal, drop this branch.
    |- Try 18 - 6 = 12. Add 12 to the number set. Current number set: [12, 7], target: 12, just two numbers left.
     |- Try 12 + 7 = 19. Evaluate 19 != 12, drop this branch.
     |- Try 12 - 7 = 5. Evaluate 5 != 12, drop this branch.
     |- Try 12 * 7 = 84. Evaluate 84 != 12, drop this branch.
     |- Try 12 / 7 = 1.7. 1.7 is a decimal, drop this branch.
    |- Try 18 * 6 = 108. Add 108 to the number set. Current number set: [108, 7], target: 12, just two numbers left.
     |- Try 108 + 7 = 115. Evaluate 115 != 12, drop this branch.
     |- Try 108 - 7 = 101. Evaluate 101 != 12, drop this branch.
     |- Try 108 * 7 = 756. Evaluate 756 != 12, drop this branch.
     |- Try 108 / 7 = 15.4. 15.4 is a decimal, drop this branch.
    |- Try 18 / 6 = 3. Add 3 to the number set. Current number set: [3, 7], target: 12, just two numbers left.
     |- Try 7 + 3 = 10. Evaluate 10 != 12, drop this branch.
     |- Try 7 - 3 = 4. Evaluate 4 != 12, drop this branch.
     |- Try 7 * 3 = 21. Evaluate 21 != 12, drop this branch.
     |- Try 7 / 3 = 2.3. 2.3 is a decimal, drop this branch.
  |- Try 16 * 9 = 144. Add 144 to the number set. Current number set: [144, 6, 18], target: 12. Options for choosing two numbers: [(144, 6), (144, 18), (6, 18)].
   |- Pick two numbers (144, 6) (numbers left: [18]). Try possible operations.
    |- Try 144 + 6 = 150. Add 150 to the number set. Current number set: [150, 18], target: 12, just two numbers left.
     |- Try 150 + 18 = 168. Evaluate 168 != 12, drop this branch.
     |- Try 150 - 18 = 132. Evaluate 132 != 12, drop this branch.
     |- Try 150 * 18 = 2700. 2700 exceeds the maximum intermediate result, drop this branch.
     |- Try 150 / 18 = 8.3. 8.3 is a decimal, drop this branch.
    |- Try 144 - 6 = 138. Add 138 to the number set. Current number set: [138, 18], target: 12, just two numbers left.
     |- Try 138 + 18 = 156. Evaluate 156 != 12, drop this branch.
     |- Try 138 - 18 = 120. Evaluate 120 != 12, drop this branch.
     |- Try 138 * 18 = 2484. 2484 exceeds the maximum intermediate result, drop this branch.
     |- Try 138 / 18 = 7.7. 7.7 is a decimal, drop this branch.
    |- Try 144 * 6 = 864. Add 864 to the number set. Current number set: [864, 18], target: 12, just two numbers left.
     |- Try 864 + 18 = 882. Evaluate 882 != 12, drop this branch.
     |- Try 864 - 18 = 846. Evaluate 846 != 12, drop this branch.
     |- Try 864 * 18 = 15552. 15552 exceeds the maximum intermediate result, drop this branch.
     |- Try 864 / 18 = 48. Evaluate 48 != 12, drop this branch.
    |- Try 144 / 6 = 24. Add 24 to the number set. Current number set: [24, 18], target: 12, just two numbers left.
     |- Try 24 + 18 = 42. Evaluate 42 != 12, drop this branch.
     |- Try 24 - 18 = 6. Evaluate 6 != 12, drop this branch.
     |- Try 24 * 18 = 432. Evaluate 432 != 12, drop this branch.
     |- Try 24 / 18 = 1.3. 1.3 is a decimal, drop this branch.
   |- Pick two numbers (144, 18) (numbers left: [6]). Try possible operations.
    |- Try 144 + 18 = 162. Add 162 to the number set. Current number set: [162, 6], target: 12, just two numbers left.
     |- Try 162 + 6 = 168. Evaluate 168 != 12, drop this branch.
     |- Try 162 - 6 = 156. Evaluate 156 != 12, drop this branch.
     |- Try 162 * 6 = 972. Evaluate 972 != 12, drop this branch.
     |- Try 162 / 6 = 27. Evaluate 27 != 12, drop this branch.
    |- Try 144 - 18 = 126. Add 126 to the number set. Current number set: [126, 6], target: 12, just two numbers left.
     |- Try 126 + 6 = 132. Evaluate 132 != 12, drop this branch.
     |- Try 126 - 6 = 120. Evaluate 120 != 12, drop this branch.
     |- Try 126 * 6 = 756. Evaluate 756 != 12, drop this branch.
     |- Try 126 / 6 = 21. Evaluate 21 != 12, drop this branch.
    |- Try 144 * 18 = 2592. 2592 exceeds the maximum intermediate result, drop this branch.
    |- Try 144 / 18 = 8. Add 8 to the number set. Current number set: [8, 6], target: 12, just two numbers left.
     |- Try 8 + 6 = 14. Evaluate 14 != 12, drop this branch.
     |- Try 8 - 6 = 2. Evaluate 2 != 12, drop this branch.
     |- Try 8 * 6 = 48. Evaluate 48 != 12, drop this branch.
     |- Try 8 / 6 = 1.3. 1.3 is a decimal, drop this branch.
   |- Pick two numbers (6, 18) (numbers left: [144]). Try possible operations.
    |- Try 18 + 6 = 24. Add 24 to the number set. Current number set: [24, 144], target: 12, just two numbers left.
     |- Try 144 + 24 = 168. Evaluate 168 != 12, drop this branch.
     |- Try 144 - 24 = 120. Evaluate 120 != 12, drop this branch.
     |- Try 144 * 24 = 3456. 3456 exceeds the maximum intermediate result, drop this branch.
     |- Try 144 / 24 = 6. Evaluate 6 != 12, drop this branch.
    |- Try 18 - 6 = 12. Add 12 to the number set. Current number set: [12, 144], target: 12, just two numbers left.
     |- Try 144 + 12 = 156. Evaluate 156 != 12, drop this branch.
     |- Try 144 - 12 = 132. Evaluate 132 != 12, drop this branch.
     |- Try 144 * 12 = 1728. Evaluate 1728 != 12, drop this branch.
     |- Try 144 / 12 = 12. Evaluate 12 == 12, target found!

Now we have found the target, let's trace back the solution:
Final step: 144 / 12 = 12
The step before: 18 - 6 = 12
The first step: 16 * 9 = 144

Output the solution in the required format:
<Solution>
16 * 9 = 144
18 - 6 = 12
144 / 12 = 12
</Solution>

[Problem]
Now, solve the following problem. Note that:
- Please carefully read the approach and examples provided above, and follow them to solve the problem.
- Please ALWAYS include your search procedure (after # Search Procedure). The search procedure should follow the format of the examples provided above.
- Please mark your answer with <Solution> and </Solution> tags. The solution should be a sequence of three equations exactly following the format of the examples above, with no additional text in between.

Numbers: [21, 15, 8, 21]
Target: 42

# Search Procedure
Initial number set: [21, 15, 8, 21], target: 42. Options for choosing two numbers: [(21, 15), (21, 8), (21, 21), (15, 8), (15, 21), (8, 21)].
 |- Pick two numbers (21, 15) (numbers left: [8, 21]). Try possible operations.
  |- Try 21 + 15 = 36. Add 36 to the number set. Current number set: [36, 8, 21], target: 42. Options for choosing two numbers: [(36, 8), (36, 21), (8, 21)].
   |- Pick two numbers (36, 8) (numbers left: [21]). Try possible operations.
    |- Try 36 + 8 = 44. Add 44 to the number set. Current number set: [44, 21], target: 42, just two numbers left.
     |- Try 44 + 21 = 65. Evaluate 65 != 42, drop this branch.
     |- Try 44 - 21 = 23. Evaluate 23 != 42, drop this branch.
     |- Try 44 * 21 = 924. Evaluate 924 != 42, drop this branch.
     |- Try 44 / 21 = 2.1. 2.1 is a decimal, drop this branch.
    |- Try 36 - 8 = 28. Add 28 to the number set. Current number set: [28, 21], target: 42, just two numbers left.
     |- Try 28 + 21 = 49. Evaluate 49 != 42, drop this branch.
     |- Try 28 - 21 = 7. Evaluate 7 != 42, drop this branch.
     |- Try 28 * 21 = 588. Evaluate 588 != 42, drop this branch.
     |- Try 28 / 21 = 1.3. 1.3 is a decimal, drop this branch.
    |- Try 36 * 8 = 288. Add 288 to the number set. Current number set: [288, 21], target: 42, just two numbers left.
     |- Try 288 + 21 = 309. Evaluate 309 != 42, drop this branch.
     |- Try 288 - 21 = 267. Evaluate 267 != 42, drop this branch.
     |- Try 288 * 21 = 6048. 6048 exceeds the maximum intermediate result, drop this branch.
     |- Try 288 / 21 = 13.7. 13.7 is a decimal, drop this branch.
    |- Try 36 / 8 = 4.5. 4.5 is a decimal, drop this branch.
   |- Pick two numbers (36, 21) (numbers left: [8]). Try possible operations.
    |- Try 36 + 21 = 57. Add 57 to the number set. Current number set: [57, 8], target: 42, just two numbers left.
     |- Try 57 + 8 = 65. Evaluate 65 != 42, drop this branch.
     |- Try 57 - 8 = 49. Evaluate 49 != 42, drop this branch.
     |- Try 57 * 8 = 456. Evaluate 456 != 42, drop this branch.
     |- Try 57 / 8 = 7.1. 7.1 is a decimal, drop this branch.
    |- Try 36 - 21 = 15. Add 15 to the number set. Current number set: [15, 8], target: 42, just two numbers left.
     |- Try 15 + 8 = 23. Evaluate 23 != 42, drop this branch.
     |- Try 15 - 8 = 7. Evaluate 7 != 42, drop this branch.
     |- Try 15 * 8 = 120. Evaluate 120 != 42, drop this branch.
     |- Try 15 / 8 = 1.9. 1.9 is a decimal, drop this branch.
    |- Try 36 * 21 = 756. Add 756 to the number set. Current number set: [756, 8], target: 42, just two numbers left.
     |- Try 756 + 8 = 764. Evaluate 764 != 42, drop this branch.
     |- Try 756 - 8 = 748. Evaluate 748 != 42, drop this branch.
     |- Try 756 * 8 = 6048. 6048 exceeds the maximum intermediate result, drop this branch.
     |- Try 756 / 8 = 94.5. 94.5 is a decimal, drop this branch.
    |- Try 36 / 21 = 1.7. 1.7 is a decimal, drop this branch.
   |- Pick two numbers (8, 21) (numbers left: [36]). Try possible operations.
    |- Try 21 + 8 = 29. Add 29 to the number set. Current number set: [29, 36], target: 42, just two numbers left.
     |- Try 36 + 29 = 65. Evaluate 65 != 42, drop this branch.
     |- Try 36 - 29 = 7. Evaluate 7 != 42, drop this branch.
     |- Try 36 * 29 = 1044. Evaluate 1044 != 42, drop this branch.
     |- Try 36 / 29 = 1.2. 1.2 is a decimal, drop this branch.
    |- Try 21 - 8 = 13. Add 13 to the number set. Current number set: [13, 36], target: 42, just two numbers left.
     |- Try 36 + 13 = 49. Evaluate 49 != 42, drop this branch.
     |- Try 36 - 13 = 23. Evaluate 23 != 42, drop this branch.
     |- Try 36 * 13 = 468. Evaluate 468 != 42, drop this branch.
     |- Try 36 / 13 = 2.8. 2.8 is a decimal, drop this branch.
    |- Try 21 * 8 = 168. Add 168 to the number set. Current number set: [168, 36], target: 42, just two numbers left.
     |- Try 168 + 36 = 204. Evaluate 204 != 42, drop this branch.
     |- Try 168 - 36 = 132. Evaluate 132 != 42, drop this branch.
     |- Try 168 * 36 = 6048. 6048 exceeds the maximum intermediate result, drop this branch.
     |- Try 168 / 36 = 4.7. 4.7 is a decimal, drop this branch.
    |- Try 21 / 8 = 2.6. 2.6 is a decimal, drop this branch.
  |- Try 21 - 15 = 6. Add 6 to the number set. Current number set: [6, 8, 21], target: 42. Options for choosing two numbers: [(6, 8), (6, 21), (8, 21)].
   |- Pick two numbers (6, 8) (numbers left: [21]). Try possible operations.
    |- Try 8 + 6 = 14. Add 14 to the number set. Current number set: [14, 21], target: 42, just two numbers left.
     |- Try 21 + 14 = 35. Evaluate 35 != 42, drop this branch.
     |- Try 21 - 14 = 7. Evaluate 7 != 42, drop this branch.
     |- Try 21 * 14 = 294. Evaluate 294 != 42, drop this branch.
     |- Try 21 / 14 = 1.5. 1.5 is a decimal, drop this branch.
    |- Try 8 - 6 = 2. Add 2 to the number set. Current number set: [2, 21], target: 42, just two numbers left.
     |- Try 21 + 2 = 23. Evaluate 23 != 42, drop this branch.
     |- Try 21 - 2 = 19. Evaluate 19 != 42, drop this branch.
     |- Try 21 * 2 = 42. Evaluate 42 == 42, target found!

Now we have found the target, let's trace back the solution:
Final step: 21 * 2 = 42
The step before: 8 - 6 = 2
The first step: 21 - 15 = 6

Output the solution in the required format:
<Solution>
21 - 15 = 6
8 - 6 = 2
21 * 2 = 42
</Solution>

Solution:
21 - 15 = 6
8 - 6 = 2
21 * 2 = 42