CREATE TABLE table_name_10 (grid INTEGER, time VARCHAR(255), laps VARCHAR(255), manufacturer VARCHAR(255))
What is the lowest Grid, when Laps is 21, when Manufacturer is Yamaha, and when Time is +18.802?
    
SQL: SELECT MIN(grid) FROM table_name_10 WHERE laps = 21 AND manufacturer = "yamaha" AND time = "+18.802"