Who is the gagarin cup winner when avangard omsk is the gagarin cup finalist?
CREATE TABLE "seasons_overview" (
  "season" text,
  "duration" text,
  "gagarin_cup_winner" text,
  "gagarin_cup_finalist" text,
  "continental_cup_winner" text,
  "top_scorer" text
);
SELECT "gagarin_cup_winner" FROM "seasons_overview" WHERE "gagarin_cup_finalist"='avangard omsk';