 On the other hand, Hungarians founded numerous parties including pro-Czechoslovak parties, founded parties with agrarian, social-democratic, Christian-socialist and other orientations, were active as sections of statewide Czechoslovak parties, had opportunities to participate in government and in the 1920s Hungarian members of parliament participated in adoption of several important laws with statewide impact.After World War II, the size of Hungarian population was decreased by Czechoslovak-Hungarian population exchange and expulsion of Hungarians who came to after the First Vienna Award or committed crimes according to Decree of Slovak National Council No.33/1945 Zb.