user: ### NOW ANSWER:
Question: What is the grid number of Sandro Cortese, who has Aprilia as the manufacturer and less than 19 laps?
Columns: ['Rider', 'Manufacturer', 'Laps', 'Time/Retired', 'Grid']
Types: ['text', 'text', 'real', 'text', 'real']
Sample row: ['Gábor Talmácsi', 'Aprilia', 19.0, '42:50.831', 2.0]
SQL:

assistant: SELECT SUM("Grid") FROM "Table" WHERE "Manufacturer" = 'Aprilia' AND "Laps" < 19.0 AND "Rider" = 'Sandro Cortese';