CREATE TABLE table_34731 ("Year" TEXT, "Class" TEXT, "Team" TEXT, "Bike" TEXT, "Races" FLOAT, "Wins" FLOAT, "Podiums" FLOAT, "Poles" FLOAT, "F. laps" FLOAT, "Points" FLOAT)

How many Podiums have a Class of 250cc, and an F laps of 0?
SELECT SUM("Podiums") FROM table_34731 WHERE "Class" = '250cc' AND "F. laps" = '0'
SELECT SUM("Podiums") FROM "table_34731" WHERE "Class" = '250cc' AND "F. laps" = '0'