SCHEMA:
CREATE TABLE table_name_10 (laps INTEGER, grid VARCHAR, constructor VARCHAR, driver VARCHAR)
USER:
Which entry has the highest laps of those with constructor Minardi - Fondmetal, driver Marc Gené, and a grid larger than 20?

QUERY:
SELECT MAX(laps) FROM table_name_10 WHERE constructor = "minardi - fondmetal" AND driver = "marc gené" AND grid > 20