How many episodes have the title "a perfect crime"?
CREATE TABLE "table1_2400842_1" (
  "episode_num" real,
  "prod_num" real,
  "title" text,
  "directed_by" text,
  "written_by" text,
  "originalairdate" text,
  "filmed" text
);
SELECT COUNT("episode_num") FROM "table1_2400842_1" WHERE "title"='\"A Perfect Crime\"';