Boys play a game of football in an empty building in Maiduguri in northeastern Nigeria on December 6, 2016. 
Jihadist group Boko Haram, which seeks to impose strict Islamic sharia law in Nigeria's mainly-Muslim north, has killed at least 20,000 people and left more than 2.6 million homeless in its six-year insurgency.  / AFP / STEFAN HEUNIS        (Photo credit should read STEFAN HEUNIS/AFP/Getty Images)