Table schema:
CREATE TABLE table_27155243_3 (total__number VARCHAR, written_by VARCHAR, directed_by VARCHAR)

Question: How many different episode numbers does the episode written by Sheri Elwood and directed by Jim Allodi have?
SQL: SELECT COUNT(total__number) FROM table_27155243_3 WHERE written_by = "Sheri Elwood" AND directed_by = "Jim Allodi"