People cool off in a fountain outside the Southbank Centre on June 30, 2015 in London, England. The UK is currently experiencing a heatwave, with temperatures of 35 degree celsius forecast tomorrow in some parts of the country. The extreme heat has already seen train cancellations and a health warning has been issued. (Photo by Rob Stothard/Getty Images)

Selena Gomez, left, and Taylor Swift arrive at the MTV Video Music Awards at the Microsoft Theater on Sunday, August 30, 2015, in Los Angeles. (Photo by Jordan Strauss/Invision/AP Photo)

A model showcases designs on the runway at MGPIN 2015 Mao Geping Makeup Trends Launch show during Mercedes-Benz China Fashion Week Spring/Summer 2015 at Beijing Hotel on October 27, 2014 in Beijing, China. (Photo by Feng Li/Getty Images)

An injured fan is helped by a riot policeman during clashes between Red Star Belgrade and Partizan Belgrade fans in the stadium before the teams' Serbian Superliga soccer match in Belgrade, April 25, 2015. Serbian league leaders Partizan Belgrade held champions and bitter city foes Red Star to a 0-0 draw in a derby match marred by bad crowd trouble before kickoff on Saturday. The start was delayed for 45 minutes after home Red Star supporters pelted riot police with seats and flares, forcing officers to retreat from the north tier that houses the club's diehard fans. (Photo by Marko Djurica/Reuters)