CREATE TABLE table_24399615_10 (episode_no VARCHAR(255), bbc_three_weekly_ranking VARCHAR(255), cable_rank VARCHAR(255))
Which episode had bbc ranking and canle ranking of n/a?
    
SQL: SELECT COUNT(episode_no) FROM table_24399615_10 WHERE bbc_three_weekly_ranking = "N/A" AND cable_rank = "N/A"