How many opponents did the team play in week 13?
CREATE TABLE "schedule" (
  "game" real,
  "date" text,
  "opponent" text,
  "result" text,
  "bills_points" real,
  "opponents" real,
  "bills_first_downs" real,
  "record" text,
  "attendance" real
);
SELECT COUNT("opponents") FROM "schedule" WHERE "game"=13;