user: Question: When Don Inglis and Ralph Smart are the writers how many episode numbers are there?
Columns: ['Episode No.', 'Prod No.', 'Title', 'Directed by', 'Written by', 'Original UK airdate']
Types: ['text', 'real', 'text', 'text', 'text', 'text']
Sample row: ['1-1', 2.0, '"View from the Villa"', 'Terry Bishop', 'Brian Clemens and Ralph Smart', 'September 11, 1960']
SQL:

assistant: SELECT COUNT("Episode No.") FROM "Table" WHERE "Written by" = 'Don Inglis and Ralph Smart';