text: Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
  ### Context:
  CREATE TABLE table_19236587_4 (original_air_date VARCHAR, series_no VARCHAR)
  ### Question:
  How many different original air dates does the episode with series number 13 have?
  ### Answer:
  SELECT COUNT(original_air_date) FROM table_19236587_4 WHERE series_no = 13