Ukraine is a country located in Eastern Europe bordering the Black Sea and the Sea of Azov. Neighboring countries include Belarus, Hungary, Moldova, Poland, Romania, Russia, and Slovakia. Most of Ukraine consists of fertile plains and plateaus, the Carpathian Mountains in the west, and the Crimean Peninsula in the extreme south. The government system is a republic; the chief of state is the president, and the head of government is the prime minister. Ukraine has a mixed economic system in which there is a limited private freedom, combined with centralized economic planning and government regulation.