Can you tell me the sum of Grid that has the Manufacturer of aprilia, and the sandro cortese?
CREATE TABLE "125cc_classification" (
  "rider" text,
  "manufacturer" text,
  "laps" real,
  "time" text,
  "grid" real
);
SELECT SUM("grid") FROM "125cc_classification" WHERE "manufacturer"='aprilia' AND "rider"='sandro cortese';