What is the lowest density of alessandria where the area is bigger than 16.02 and altitude is less than 116?
CREATE TABLE "communes" (
  "rank" text,
  "city" text,
  "population" real,
  "area_km_2" real,
  "density_inhabitants_km_2" real,
  "altitude_mslm" real
);
SELECT MIN("density_inhabitants_km_2") FROM "communes" WHERE "area_km_2">16.02 AND "altitude_mslm"<116 AND "city"='alessandria';