What is the lowest population of alessandria where the altitude is less than 197 and density is less than 461.8?
CREATE TABLE "communes" (
  "rank" text,
  "city" text,
  "population" real,
  "area_km_2" real,
  "density_inhabitants_km_2" real,
  "altitude_mslm" real
);
SELECT MIN("population") FROM "communes" WHERE "altitude_mslm"<197 AND "city"='alessandria' AND "density_inhabitants_km_2"<461.8;