In 1875, Tesla enrolled at Austrian Polytechnic in Graz, Austria, on a Military Frontier scholarship. During his first year, Tesla never missed a lecture, earned the highest grades possible, passed nine exams (nearly twice as many required), started a Serbian culture club, and even received a letter of commendation from the dean of the technical faculty to his father, which stated, "Your son is a star of first rank." Tesla claimed that he worked from 3 a.m. to 11 p.m., no Sundays or holidays excepted. He was "mortified when [his] father made light of [those] hard won honors." After his father's death in 1879, Tesla found a package of letters from his professors to his father, warning that unless he were removed from the school, Tesla would be killed through overwork. During his second year, Tesla came into conflict with Professor Poeschl over the Gramme dynamo, when Tesla suggested that commutators weren't necessary. At the end of his second year, Tesla lost his scholarship and became addicted to gambling. During his third year, Tesla gambled away his allowance and his tuition money, later gambling back his initial losses and returning the balance to his family. Tesla said that he "conquered [his] passion then and there," but later he was known to play billiards in the US. When exam time came, Tesla was unprepared and asked for an extension to study, but was denied. He never graduated from the university and did not receive grades for the last semester.