Argentina is a country in South America bordering the Southern Atlantic Ocean. Neighboring countries include Bolivia, Brazil, Chile, Paraguay, and Uruguay. Argentina's continental area is between the Andes mountain range in the west and the Atlantic Ocean in the east. Diverse geographical landscapes produce varying climates from tropical in the north to tundra in the far south. The government system is a republic; the president is the chief of state and head of government. Argentina has a mixed economic system which includes a variety of private freedom, combined with centralized economic planning and government regulation. Argentina is a member of the Common Market of the South (Mercosur).