What is the lowest number of games loss with a Points difference of 40 - 17, and over 6 games?
CREATE TABLE "world_championship_group_c_bulgaria" (
  "games" real,
  "drawn" real,
  "lost" real,
  "points_difference" text,
  "points" real
);
SELECT MIN("lost") FROM "world_championship_group_c_bulgaria" WHERE "points_difference"='40 - 17' AND "games">6;