Table: san_marino_1995_gp
Columns: driver
constructor
laps
time_retired
grid

Question: When driver heinz-harald frentzen has a number of laps greater than 60, what is the sum of grid?
SQL: SELECT COUNT("grid") FROM san_marino_1995_gp WHERE "laps" > 60 AND "driver" = 'heinz-harald frentzen'