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_name_37 ( episode INTEGER, performer_4 VARCHAR, performer_2 VARCHAR )

### Question ###
What is the sum of the episode numbers where chip esten is the 4th performer and christopher smith was the 2nd performer?

### Accurate SQL ###

SELECT SUM(episode) FROM table_name_37 WHERE performer_4 = "chip esten" AND performer_2 = "christopher smith"