How many episode numbers are there on the show whose first couple was Stuart and Pegah>?
CREATE TABLE "series_2" (
  "num" real,
  "airdate" text,
  "no_of_couples" real,
  "1st_couple" text,
  "2nd_couple" text,
  "3rd_couple" text,
  "4th_couple" text,
  "viewers_millions" text,
  "itv1_weekly_ranking" text
);
SELECT COUNT("num") FROM "series_2" WHERE "1st_couple"='Stuart and Pegah';