CREATE TABLE table_36226 ("Date" TEXT, "Race" TEXT, "Race track" TEXT, "Category" TEXT, "Lap length" TEXT)

What is the Lap Length of the race with a Grand Prix Fia Category?
SELECT "Lap length" FROM table_36226 WHERE "Category" = 'grand prix fia'
SELECT "Lap length" FROM "table_36226" WHERE "Category" = 'grand prix fia'