Ukrainian Air Force officers attend a graduation ceremony at the National University of Defence of Ukraine in Kiev, April 24, 2015. (Photo by Gleb Garanich/Reuters)

A competitor participates in the Tough Mudder challenge near Henley-on-Thames in southern England May 2, 2015. (Photo by Eddie Keogh/Reuters)

A helicopter drops water over a wildfire as a firefighter works to contain it in Benahavis, southern Spain, May 19, 2015. (Photo by Jon Nazca/Reuters)

A participant smiles at the annual Christopher Street Day parade on Kurfuerstendamm in Berlin, Germany, June 27, 2015. (Photo by Fabrizio Bensch/Reuters)

A woman sells vegetables near a Metro train station in downtown Lima, Peru December 1, 2015. (Photo by Mariana Bazo/Reuters)

Participants pose for a photographers during the Miss Iraq Pageant in Baghdad, December 19, 2015. (Photo by Ahmed Saad/Reuters)

People are reflected in mirrors as they walk in a busy shopping district in Tokyo, Japan, December 25, 2015. (Photo by Thomas Peter/Reuters)

A woman performs during a march to commemorate International Day for the Elimination of Violence Against Women, in Bogota, November 25, 2015. (Photo by John Vizcaino/Reuters)