Nigeria is a country located in West Africa with a coast on the Gulf of Guinea and the Atlantic Ocean. Neighboring countries include Benin, Cameroon, Chad, and Niger. The geography ranges from southern coastal swamps to tropical forests, woodlands, grasslands, and semi-desert in the north. The government system is a federal republic; the chief of state and head of government is the president. Nigeria has a mixed economic system which includes a variety of private freedom, combined with centralized economic planning and government regulation. Nigeria is a member of the Economic Community of West African States (ECOWAS).