A competitor reacts as she takes part in the “Tough Guy” adventure race near Wolverhampton, central England, on January 29, 2017. The Tough Guy event, which is being held for the final time in its 30th year, challenges thousands of competitors to run a gruelling course whilst negotiating over 200 obstacles including: water, fire, and tunnels. (Photo by Oli Scarff/AFP Photo)

Students of the General Yermolov Cadet School take part in combined military training with members of a local youth military patriotic club at a boot camp of the Russkiye Vityazi (Russian Knights) military patriotic club in the village of Sengileyevskoye outside Stavropol, Russia February 8, 2017. (Photo by Eduard Korniyenko/Reuters)

Miss Langata Prison 2016 Ruth Kamande poses for a photograph as female inmates participate in a fashion parade as part of their Valentine's Day celebration, dubbed “love behind bars” inside the Langata Women Maximum Security Prison in Kenya's capital Nairobi, February 14, 2017. (Photo by Thomas Mukoya/Reuters)

A mahout walks with an elephant after bathing him in a river, before taking part in an elephant festival, which organisers say aims to raise awareness about elephants, in Sayaboury province, Laos February 17, 2017. (Photo by Phoonsab Thevongsa/Reuters)

A woman works at a factory producing clay pots at Phu Lang pottery village in Bac Ninh province, Vietnam, May 14, 2015. The village is part of an old pottery triangle in northern Vietnam which includes Bat Trang and Tho Ha, and has been producing pottery since the 13th century, according to local media. (Photo by Reuters/Kham)

Chinese military medics take part in a parade commemorating the 70th anniversary of Japan's surrender during World War II held in front of Tiananmen Gate in Beijing, Thursday, September 3, 2015. (Photo by Ng Han Guan/AP Photo)

A pilot inflates a hot air balloon while taking part in the 38th International Balloon Festival of Chateau-d'oex, Switzerland, 23 January 2016. The festival takes place from 23 to 31 January. (Photo by Vincent Vannay/EPA)

Revellers take part in the traditional “Weiberfastnacht” (Women's Carnival) celebration in Mainz, Germany, February 4, 2016. Germany is celebrating its traditional carnival with tight security after assaults on women during New Year's Eve celebrations across the country. (Photo by Kai Pfaffenbach/Reuters)