In how many episodes was Dave's team made up of David Walliams and Louis Walsh?
CREATE TABLE "series_3" (
  "episode" text,
  "first_broadcast" text,
  "seans_team" text,
  "daves_team" text,
  "scores" text
);
SELECT COUNT("episode") FROM "series_3" WHERE "daves_team"='David Walliams and Louis Walsh';