When don inglis and ralph smart are the writers how many episode numbers are there?
CREATE TABLE table_25046766_1 (
    episode_no VARCHAR,
    written_by VARCHAR
)
SELECT COUNT(episode_no) FROM table_25046766_1 WHERE written_by = "Don Inglis and Ralph Smart"
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: When don inglis and ralph smart are the writers how many episode numbers are there? ### Input: CREATE TABLE table_25046766_1 (
    episode_no VARCHAR,
    written_by VARCHAR
) ### Response: SELECT COUNT(episode_no) FROM table_25046766_1 WHERE written_by = "Don Inglis and Ralph Smart"