What is the election date for those politicians who left office on 1850-11-15?
CREATE TABLE "elections_to_congress_of_deputies" (
  "election_number" real,
  "election_date" text,
  "district" text,
  "province" text,
  "took_office" text,
  "left_office" text
);
SELECT COUNT("election_date") FROM "elections_to_congress_of_deputies" WHERE "left_office"='1850-11-15';