Riot security forces clash with demonstrators as a motorcycle is set on fire during a protest against Venezuelan President Nicolas Maduro's government in San Cristobal, Venezuela May 29, 2017. (Photo by Carlos Eduardo Ramirez/Reuters)

A little girl holding her newborn sister waits for their turn in a queue during a vaccination campaign under the supervision of the Syrian Arab Red Crescent (SARC) humanitarian nonprofit organization, in the besieged Syrian town of Douma, Syria, 23 May 2017. According to a statement from SARC, in the city of Douma some 12,809 children under the age of five were immunized in a vaccination campaign to prevent measles and poliomyelitis. The campaign was the first of its kind with the participation of 100 volunteers. SARC has been delivering vaccines to 17 health centers approved for vaccination campaigns in towns and villages in the Eastern Ghouta area. (Photo by Mohammed Badra/EPA)

Female soldiers march during a military parade marking the country's Independence Day in Caracas, Venezuela, Wednesday, July 5, 2017. Venezuela is marking 206 years of their declaration of independence from Spain. (Photo by Ariana Cubillos/AP Photos)

In this May 14, 2016 photo, children wearing their school backpacks climb on a cliff using a bamboo ladder on their way home from school in Zhaojue county, southwest China's Sichuan province. A village in China's mountainous west where schoolchildren must climb an 800-meter (2,625-foot)-high bamboo ladder secured to a sheer cliff face may get a set of steel stairs to improve it's safety. (Photo by Chinatopix via AP Photo)

A man lies in the sea grass at a beach on July 18, 2016 in Qingdao, Shandong Province of China. The enteromorpha prolifera spread on the beaches in Qingdao and were under clearing. (Photo by VCG/VCG via Getty Images)

A jockey takes part in a traditional cattle race or “Pacu Jawi”, to mark the end of the rice harvest in Tanah Datar, West Sumatra, Indonesia, August 13, 2016 in this photo taken by Antara Foto. (Photo by Hafiz Mubarak A./Reuters/Antara Foto)

A woman plays around as she walks across a glass-bottomed suspension bridge in a scenic zone in Pingjiang county in southern China's Hunan province Thursday, September 24, 2015. The bridge, 300 meters (984 feet) long and 180 meters (590 feet), opened to visitors on Thursday for the first time since its conversion from a regular suspension bridge was completed. (Photo by Chinatopix Via AP Photo)

Fish weighing over 80 kilogram is cooked in a hotpot during a food festival in Zhengzhou, Henan province, China, October 17, 2015. (Photo by Reuters/Stringer)