What is the total number of episodes listed with a production code of 306?
CREATE TABLE table_18424435_4 (
    _number VARCHAR,
    production_code VARCHAR
)
SELECT COUNT(_number) FROM table_18424435_4 WHERE production_code = 306
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: What is the total number of episodes listed with a production code of 306? ### Input: CREATE TABLE table_18424435_4 (
    _number VARCHAR,
    production_code VARCHAR
) ### Response: SELECT COUNT(_number) FROM table_18424435_4 WHERE production_code = 306