What are the lowest number of points with a Year of 1978, and a Chassis of ensign n177?
CREATE TABLE "complete_world_championship_formula_one_" (
  "year" real,
  "entrant" text,
  "chassis" text,
  "engine" text,
  "points" real
);
SELECT MIN("points") FROM "complete_world_championship_formula_one_" WHERE "year"=1978 AND "chassis"='ensign n177';