Students of the General Yermolov Cadet School wait to board an airplane for a parachute jump at an airdrome in the village of Novomaryevskaya outside the southern city of Stavropol, Russia, May 13, 2016. (Photo by Eduard Korniyenko/Reuters)

A general view shows smoke and volcanic ashes billowing from volcano Cotopaxi in Pedregal, Ecuador, late 07 October 2015. (Photo by Jose Jacome/EPA)

A grave cleaner holds up a skull during exhumation works at the Cemetery General in Guatemala City May 24, 2013. If a lease on a grave has expired or not been paid, grave cleaners will break open the crypts to remove and rebury the bodies. (Photo by Jorge Dan Lopez/Reuters)

General Atmosphere at 2014 New York Comic Con – Day 3 at Jacob Javitz Center on October 11, 2014 in New York City. (Photo by Laura Cavanaugh/Getty Images)

General view of a herbal store in Cairo, Egypt January 10, 2017. In an economic crisis that has led to a shortage of medicines, Egyptians are skipping trips to drug stores and instead turning to herbal remedies to treat every-day illnesses. (Photo by Mohamed Abd El Ghany/Reuters)

Two guards perform an execution in China, one holding the gun, the other holding a mask over the victim's face. (Photo by General Photographic Agency/Getty Images). Circa 1925

A general view of the landslide-hit Miancu Village on July 3, 2011 in Maixian County, Sichuan Province of China. Eight people are still missing after a dormitory building of a chemical plant was hit by a rain-triggered mudslide in Maoxian County on Sunday morning. Rescue efforts are underway. (Photo by ChinaFotoPress/Getty Images)

Three Chinese soldiers at the time of a civil war in China. (Photo by General Photographic Agency/Getty Images). 1922