Name the total number of years for chassis of maserati 250f and points less than 0
CREATE TABLE "complete_formula_one_world_championship_" (
  "year" real,
  "entrant" text,
  "chassis" text,
  "engine" text,
  "points" real
);
SELECT COUNT("year") FROM "complete_formula_one_world_championship_" WHERE "chassis"='maserati 250f' AND "points"<0;