Table schema:
CREATE TABLE table_name_86 (format VARCHAR, region_4 VARCHAR, _number_episodes VARCHAR, _number_disc_s_ VARCHAR)

Question: What was the format for the 4 disc season that had less than 22 episodes and n/a for region 4?
SQL: SELECT format FROM table_name_86 WHERE _number_episodes < 22 AND _number_disc_s_ = 4 AND region_4 = "n/a"