Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_25046766_1 (episode_no VARCHAR, written_by VARCHAR)

### Question ###
When don inglis and ralph smart are the writers how many episode numbers are there?

### Accurate SQL ###

SELECT COUNT(episode_no) FROM table_25046766_1 WHERE written_by = "Don Inglis and Ralph Smart"