In this timed-exposure night photo taken early on February 12, 2017, Mount Sinabung volcano spews reddish smoke and ash, as seen from the Karo district in North Sumatra province. Activity levels have increased in the past week, with Sinabung shooting hot ash clouds into the sky dozens of times, according to the local volcano monitoring agency. (Photo by AFP Photo/Stringer)

Battle-weary American troops withdraw from Yong San in Korea. (Photo by Keystone/Getty Images). 1950

Tong Jieping, 44-year-old mentally disabled patient, is chained by his foot inside his room, in Qunxing village of Wangjiang county, Anhui province, China, July 14, 2015. Tong was diagnosed mentally ill when he was in his 20s. His parents, both in their 70s, could not afford the medical treatments so they had to lock him up in chains to prevent him from running away, according to Tong's family. (Photo by Reuters/Stringer)

People try to board a goverment bus during the second day of a suspension of public transport services in Apopa, El Salvador July 28, 2015. Violent gangs in El Salvador ordered bus drivers to strike on Monday in a conflict that has killed six people and left thousands of commuters stranded on the streets of the Central American capital, police and bus company officials said. (Photo by Jose Cabezas/Reuters)

People dressed as zombies participate in a parade for World Zombie Day 2016 in London's West End, Britain on October 9, 2016. (Photo by Splash News and Pictures)

Disguised revellers parade on the occasion of the Cortege during the Carnival in Basel, Switzerland, February 17, 2016. (Photo by Georgios Kefalas/EPA)

A worker refreshes himself with a fan after loading a container with rice bags at an export plant in the central Chainat province in Thailand, December 16, 2015. (Photo by Jorge Silva/Reuters)