When  david ashburn richard westbrook is the gt3 winner and 1 is the round what is the length?
CREATE TABLE "calendar" (
  "round" real,
  "circuit" text,
  "date" text,
  "length" text,
  "pole_position" text,
  "gt3_winner" text,
  "gt4_winner" text
);
SELECT "length" FROM "calendar" WHERE "round"=1 AND "gt3_winner"='David Ashburn Richard Westbrook';