Cuban 15-year-old Mayelis sits with her new apple-shaped haircut in Havana March 28, 2013. In a world where population growth is exploding and a region where countries have high birth rates and low median ages, Cuba's population is declining and getting older. Like many underdeveloped countries, Cuba struggles to hold on to its best and brightest, but unlike most others, it faces the added difficulty of doing so at the doorstep of a hostile superpower with an open door immigration policy for Cubans. Picture taken March 28, 2013. To match Feature CUBA-YOUTH/ REUTERS/Desmond Boylan (CUBA - Tags: SOCIETY)