What was the aggregate for a team #2 of Okk Beograd?
CREATE TABLE "first_round" (
  "team_num1" text,
  "agg" text,
  "team_num2" text,
  "1st_leg" text,
  "2nd_leg" text
);
SELECT "agg" FROM "first_round" WHERE "team_num2"='okk beograd';