What episode number was written by Gregg Hurwitz?
CREATE TABLE "table1_24938621_3" (
  "no" real,
  "num" real,
  "title" text,
  "directed_by" text,
  "written_by" text,
  "original_air_date" text,
  "production_code" text,
  "u_s_viewers_million" text
);
SELECT "no" FROM "table1_24938621_3" WHERE "written_by"='Gregg Hurwitz';