Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_38081 ( "Rider" text, "Manufacturer" text, "Laps" real, "Time/Retired" text, "Grid" real )

### Question ###
What is the grid number of Sandro Cortese, who has Aprilia as the manufacturer and less than 19 laps?

### Accurate SQL ###

SELECT SUM("Grid") FROM table_38081 WHERE "Manufacturer" = 'aprilia' AND "Laps" < '19' AND "Rider" = 'sandro cortese'