Angola is governed under the constitution of 2010. The executive branch is headed by the president; the leader of the party or coalition that receives the most votes in the National Assembly elections is elected to the office. The president, who serves as both head of state and head of government, may serve two five-year terms. The unicameral National Assembly has 220 members who are elected by proportional vote on a national (130) or provincial (90) basis for four-year terms. Adminstratively, the country is divided into 18 provinces.