human
Considering the provided database schema and associated query, produce SQL code to retrieve the answer to the query. 
###Database Schema: Series no., Season no., Title, Directed by, Written by, Original air date, Production code, U.S. viewers (millions)
###Question: at most what number in the series was the episode "chet episode"?
gpt
SELECT MAX Series no. FROM table WHERE Title = "Chet Episode"