What is the 1st leg when the 2nd leg was 67-83?
CREATE TABLE "first_preliminary_round" (
  "team_num1" text,
  "agg" text,
  "team_num2" text,
  "1st_leg" text,
  "2nd_leg" text
);
SELECT "1st_leg" FROM "first_preliminary_round" WHERE "2nd_leg"='67-83';