import json

def lambda_handler(event, context):
    number_1 = int(event['key1'])
    number_2 = int(event['key2'])
    return {"number" : abs(number_1 - number_2)}

import json
import time

def lambda_handler(event,context):
    number_1 = event['key1']
    number_2 = event['key2']
    return {"number" : abs(number_1 - number_2)}
--- 
+++ 
@@ -1,7 +1,6 @@
 import json
-import time
 
-def lambda_handler(event,context):
-    number_1 = event['key1']
-    number_2 = event['key2']
+def lambda_handler(event, context):
+    number_1 = int(event['key1'])
+    number_2 = int(event['key2'])
     return {"number" : abs(number_1 - number_2)}
Add int() function for casting from string to integer
