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 stadium (city VARCHAR, opening_year INTEGER)
  ### Question:
  How many cities have a stadium that was opened before the year of 2006?
  ### Answer:
  SELECT COUNT(DISTINCT city) FROM stadium WHERE opening_year < 2006