What was the score on the first leg when gimnasia de mendoza played at home for the second leg?
CREATE TABLE "knockout_stages" (
  "home_1st_leg" text,
  "home_2nd_leg" text,
  "1st_leg" text,
  "2nd_leg" text,
  "aggregate" text
);
SELECT "1st_leg" FROM "knockout_stages" WHERE "home_2nd_leg"='gimnasia de mendoza';