CREATE TABLE "round_13" (
  "home_team" text,
  "home_team_score" text,
  "away_team" text,
  "away_team_score" text,
  "venue" text,
  "crowd" real,
  "date" text
);

Question: In which of North Melbourne's away games was there the lowest crowd?
SQL: SELECT MIN("crowd") FROM "round_13" WHERE "away_team"='north melbourne';