Children displaced as a result of Boko Haram attacks in the northeast region of Nigeria, run at a camp for internally displaced persons (IDP) in Yola, Adamawa State January 13, 2015. Boko Haram says it is building an Islamic state that will revive the glory days of northern Nigeria's medieval Muslim empires, but for those in its territory life is a litany of killings, kidnappings, hunger and economic collapse. (Photo by Afolabi Sotunde/Reuters)

An Egyptian actress working at the Pharaonic Village simulates ancient agriculture scenes during a show marking Sham el-Nessim, or “smelling the breeze”, in Giza, Egypt, Monday, April 13, 2015. The holiday signifies the arrival of Spring, a uniquely Egyptian tradition practiced since the days of the Pharaohs. (Photo by Amr Nabil/AP Photo)

A woman walks past servicemen of the self-proclaimed Donetsk People's Republic (DNR), who take part in a rehearsal for the Victory Day parade in Donetsk, Ukraine on May 3, 2018. (Photo by Alexander Ermochenko/Reuters)

Waura Indians wrestle during this year's “quarup”, a ritual held over several days to honour in death a person of great importance to them, in Xingu National Park, Mato Grosso State, Brazil August 25, 2013. (Photo by Ueslei Marcelino/Reuters)

Gers, traditional Mongolian tents, are seen on a hill in an area known as a ger district in Ulan Bator June 26, 2013. Approximately 60 percent of the population of Ulan Bator live in settlements known as ger districts and in many cases residents have limited access to basic services such as water and sanitation. According to a 2010 National Population Center census, every year between thirty and forty thousand people migrate from the countryside to the capital Ulan Bator. Ger districts in the city have been expanding rapidly in recent years. Mongolia is the world's least densely populated country, with 2.8 million people spread across an area around three times the size of France. (Photo by Carlos Barria/Reuters)

A traffic police woman whistles at a pedestrian, Monday, July 27, 2015, in Pyongyang, North Korea where its citizens are having a one-day national holiday to celebrate the country's 62nd anniversary of the armistice that ended the Korean War. (Photo by Wong Maye-E/AP Photo)

Queen Elizabeth II (as Princess Elizabeth) writing at her desk in Windsor Castle, Berkshire. (Photo by Lisa Sheridan/Studio Lisa/Getty Images). 30th May 1944

Russian Police academy female cadets march during a rehearsal for the Victory Day military parade at Dvortsovaya (Palace) Square in St Petersburg, Russia, Wednesday, May 7, 2014. Victory Day, marking the defeat of Nazi Germany, is Russia's most important secular holiday celebrated on May 9. (Photo by Dmitry Lovetsky/AP Photo)