Fifth-grade students of the General Yermolov Cadet School get prepared before their first military tactical exercise on the ground, which includes radiation resistance classes, forest survival studies and other activities, in Stavropol, Russia, September 10, 2016. Picture taken September 10, 2016. (Photo by Eduard Korniyenko/Reuters)

Palestinian boy Mohammad al-Bana, 10, sells mints at a market in Gaza City March 29, 2016. Bana, whose father is unemployed, earns around 10 Shekels ($2.5) per day. The boy starts working after finishing school. He hopes to continue education and become an engineer in the future. (Photo by Mohammed Salem/Reuters)

Sheep walk as they are herded to summer pastures in Serra da Estrela, near Seia, Portugal June 27, 2015. In late June, shepherds young and old in the Seia region of central Portugal start guiding sheep, goats and cattle to the Serra da Estrela, the country’s highest mountains, in search of better pastures. There they stay until the end of September. Modern-day shepherds may have mobile phones to keep in touch with family and friends, but their lifestyle has changed little for centuries. The sound of cowbells and the bark of longhaired mastiffs starts early in the morning as the animals – often decorated with traditional woollen balls on their horns – are herded up steep, narrow paths. (Photo by Rafael Marchante/Reuters)

Chinese women ride a bicycle together on a street September 10, 2014 in Beijing, China. (Photo by Kevin Frayer/Getty Images)

A woman sorts tobacco leaves at the Cohiba cigar factory “El Laguito” in Havana September 10, 2012. (Photo by Desmond Boylan/Reuters)

A cat sits in the flooding waters from Hurricane Matthew in downtown Nichols, South Carolina, October 10, 2016. (Photo by Randall Hill/Reuters)

People dance in a park on a foggy day in Huai'an, Jiangsu province, China October 10, 2017. (Photo by Reuters/China Stringer Network)

A dog jumps into the pool during the Flying Dogs competition in Kamnik, Slovenia, September 10, 2016. (Photo by Srdjan Zivulovic/Reuters)