JOHANNESBURG, SOUTH AFRICA - DECEMBER 10 : US President Barack Obama (L) greets Cuban President Raul Castro during the memorial service for the late South African President Nelson Mandela at FNB Stadium on December 10, 2013 in Johannesburg, South Africa. Mandela, 95, passed away at his home in Johannesburg on December 5 after a prolonged battle against health problems in recent months. (Photo by Erhan Sevenler/Anadolu Agency/Getty Images)
