How much Area (km 2) has a Common of collegno, and a Population smaller than 50137?
CREATE TABLE "see_also" (
  "rank" text,
  "common_of" text,
  "population" real,
  "area_km_2" real,
  "density_inhabitants_km_2" real,
  "altitude_mslm" real
);
SELECT COUNT("area_km_2") FROM "see_also" WHERE "common_of"='collegno' AND "population"<50137;