A hippopotamus performs during a show at the circus in Krasnoyarsk, Siberia, Russia, July 7, 2016. (Photo by Ilya Naymushin/Reuters)

Cambodian children sleep on a pavement at a park in Phnom Penh on July 8, 2016. (Photo by Tang Chhin Sothy/AFP Photo)

Free Syrian Army fighters stand near an ambulance on the eastern edge of the northern Syrian town of al-Bab, Syria, February 27, 2017. (Photo by Khalil Ashawi/Reuters)

Models wait backstage during the Ukrainian Fashion Week in Kiev, October 16, 2015. (Photo by Valentyn Ogirenko/Reuters)

Two female soldiers have their picture taken by an army colleague at Mangyongdae. (Photo by Gavin John/Mediadrumworld.com)

In this Monday, June 5, 2017, file photo, an Indian woman walks as se searches for recyclable materials at a garbage dumping site on the outskirts of Gauhati, Assam state, India. (Photo by Anupam Nath/AP Photo)

The moon rises behind the skyline and financial district in Toronto, November 25, 2015. (Photo by Mark Blinch/Reuters)

A woman walks past a caricature of Britain's Foreign Secretary Boris Johnson in east London, Britain November 18, 2016. (Photo by Andrew Winning/Reuters)