 Complete the following phrase:  Born in Belišće, Osijek-Baranja, Ljubek competed in four Summer Olympics where he won four medals. This included two golds C-1 1000 m: 1976, C-2 500 m: 1984 with Mirko Nišović, one silver C-2 1000 m: 1984 with Mirko Nišović, and one bronze C-1 500 m: 1976. His trainer was Laszlo Hingl. He also won ten medals at the ICF Canoe Sprint World Championships with four golds C-1 1000 m: 1978, C-2 500 m: 1982, 