What is the tie number in the game on 5 January 1986 where Exeter City is the away team?
CREATE TABLE "third_round_proper" (
  "tie_no" text,
  "home_team" text,
  "score" text,
  "away_team" text,
  "date" text
);
SELECT "tie_no" FROM "third_round_proper" WHERE "date"='5 january 1986' AND "away_team"='exeter city';