Who was the second couple for the episode having an ITV1 ranking of 29?
CREATE TABLE "series_1" (
  "num" real,
  "airdate" text,
  "no_of_couples" real,
  "first_couple" text,
  "second_couple" text,
  "third_couple" text,
  "fourth_couple" text,
  "viewers_millions" text,
  "itv1_weekly_ranking" real
);
SELECT "second_couple" FROM "series_1" WHERE "itv1_weekly_ranking"=29;