How many rounds were 2r?
CREATE TABLE table_16645 (
    "Edition" real,
    "Zone" text,
    "Round" text,
    "Date" text,
    "Against" text,
    "Surface" text,
    "Opponent" text,
    "Outcome" text,
    "Result" text
)
SELECT COUNT("Result") FROM table_16645 WHERE "Round" = '2R'
Below are sql tables schemas paired with instruction that describes a task. Using valid SQLite, write a response that appropriately completes the request for the provided tables. ### Instruction: How many rounds were 2r? ### Input: CREATE TABLE table_16645 (
    "Edition" real,
    "Zone" text,
    "Round" text,
    "Date" text,
    "Against" text,
    "Surface" text,
    "Opponent" text,
    "Outcome" text,
    "Result" text
) ### Response: SELECT COUNT("Result") FROM table_16645 WHERE "Round" = '2R'