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 actor ( last_name VARCHAR )

### Question ###
How many different last names do the actors and actresses have?

### Accurate SQL ###

SELECT COUNT(DISTINCT last_name) FROM actor