Angola (full name, The Republic of Angola) covers an area of approximately 1,250,000 sq km. Its terrain consists of a narrow coastal plain rising sharply to an extensive interior plateau. Angola borders the Democratic Republic of the Congo, Namibia and Zambia, and has 1,600 km of coastline. The country is divided into 18 provinces: Benguela, Bie, Cabinda, Cuando Cubango, Cuanza Norte, Cuanza Sul, Cunene, Huambo, Huila, Luanda, Lunda Norte, Lunda Sul, Malanje, Moxico, Namibe, Uige and Zaire. Luanda is the capital, with a time difference of 1 hour ahead of GMT. The currency is the kwanza, and main exports include oil, diamonds, minerals, coffee, fish and timber. The population of approximately 13,000,000 people comprises an ethnic makeup that is 37% Ovimbundu, 25% Kimbundu and 13% Bakongo. The official language is Portuguese, and the predominant religions are Christianity and indigenous beliefs.