 Complete the following phrase:  Jan Barták is a former ice dancer who represented Czechoslovakia. With Jana Beránková, he is the 1981 Prague Skate champion, the 1981 NHK Trophy bronze medalist, the 1982 Ennia Challenge Cup silver medalist, and a two-time Czechoslovak national champion. The duo finished in the top ten at four ISU Championships  1981 Europeans in Innsbruck, Austria; 1981 Worlds in Hartford, Connecticut, United States; 