Croatia is a country in Central Europe and Southeastern Europe on the Adriatic Sea. Neighboring countries include Bosnia and Herzegovina, Hungary, Montenegro, Serbia, and Slovenia. Geographically, Croatia is diverse with flat plains, low mountains, and islands. Croatia controls most land routes from Western Europe to the Aegean Sea and Turkish Straits. The government system is a presidential/parliamentary democracy. The chief of state is the president, and the head of government is the prime minister. Croatia has a mixed economic system which includes a variety of private freedom, combined with centralized economic planning and government regulation. Croatia is a member of the European Union (EU).