A man stands in front of a poster created by artist Tomoko Konoike, one of 20 posters officially selected for the Tokyo Olympics and Paralympics, at the Museum of Contemporary Art Tokyo Monday, January 6, 2020. The official posters are out for this year's Tokyo Olympics and Paralympics. The 20 posters have been created by 19 artists in fields ranging from painting, graphic design, and photography. Calligraphy and Japanese manga are also represented. (Photo by Jae C. Hong/AP Photo)

A zookeeper feeds a hippopotamus with a watermelon in its enclosure in Belgrade's zoo, Serbia, July 20, 2015. Temperatures in Serbia have risen up to 40 degrees Celsius (104 degrees Fahrenheit), according to official meteorological data. (Photo by Marko Djurica/Reuters)

Boys eat at a rubbish dump where they are collecting recyclable waste outside Yemen's Red Sea port city of Houdieda January 20, 2016. (Photo by Abduljabbar Zeyad/Reuters)

A participant jumps on vintage skis during a traditional historical ski race in the northern Bohemian town of Smrzovka, Czech Republic, February 20, 2016. (Photo by David W. Cerny/Reuters)

An Iraqi soldier stands guard as a pipeline burns in the background after an explosion 30 kilometers (20 miles) northeast of Tikrit, Iraq, Monday, February 11, 2008. (Photo by Bassem Daham/AP Photo)

A man jokingly poses with a new installation of British graffiti artist Banksy's art in New York, October 20, 2013. (Photo by Carlo Allegri/Reuters)

Peter Dinklage, left, and Lena Headey attend the 67th Primetime Emmy Awards on Sunday, September 20, 2015, at the Microsoft Theater in Los Angeles. (Photo by Alex Berliner/Invision for the Television Academy/AP Images)

A supporter of China's President Xi Jinping waits on the Mall for him to pass during his ceremonial welcome, in London, Britain, October 20, 2015. Xi is on a State visit to Britain. (Photo by Peter Nicholls/Reuters)