After years of mopping floors, cleaning toilets and taking out trash at Columbia University, a refugee from war-torn Yugoslavia yesterday reaped his reward: a bachelor’s degree in classics.

As a Columbia employee, Gac Filipaj, a 52-year-old janitor, didn’t have to pay for his classes.

His graduation with honors capped a dozen years of studies, including readings in ancient Latin and Greek.

“This is a man with great pride, whether he’s doing custodial work or academics,” said Peter Awn, dean of Columbia’s School of General Studies and professor of Islamic studies. “He is immensely humble.”