Singers Chris Daughtry and Rachel Platten attend the 2017 Billboard Music Awards at T-Mobile Arena on May 21, 2017 in Las Vegas, Nevada. (Photo by Chris Polk/BBMA2017/Getty Images for DCP)

Singer Ariana Grande (C) performs “Side by Side” during the 2016 American Music Awards in Los Angeles, California, U.S., November 20, 2016. (Photo by Mario Anzuoni/Reuters)

DJ David Guetta (R) and rapper Nicki Minaj perform onstage during the 2017 Billboard Music Awards at T-Mobile Arena on May 21, 2017 in Las Vegas, Nevada. (Photo by Mario Anzuoni/Reuters)

Girls cry as they get separated from their family at the border line dividing Macedonia and Greece August 21, 2015. At least 1,000 migrants and refugees pressed against Macedonian police lines on the Greek-Macedonian border on Friday and at least 10 people appeared to faint in the crush. People could be heard screaming and medical workers raced to treat those who passed out or were hurt. The crush ensued after police let several hundred through into Macedonia, having kept them out since Thursday under an emergency decree. (Photo by Ognen Teofilovski/Reuters)

A girl plays with colourful papers at the 23rd Sziget (Island) Festival on Shipyard Island in Budapest, Hungary, 13 August 2015. The festival is one of the biggest cultural events of Europe, offering art exhibitions, theatrical and circus performances and music concerts. Almost 200 performers from 47 countries will entertain the hundreds of thousands of visitors from 11 to 18 August. (Photo by Balazs Mohai/EPA)

Dani (L) and Bella Thorne arrive at the 2016 American Music Awards in Los Angeles, California, U.S., November 20, 2016. (Photo by Danny Moloshok/Reuters)

Recording artists Demi Lovato (L) and Iggy Azalea perform on the Pepsi Stage, during the 2015 MTV Video Music Awards, at The Orpheum Theatre on August 30, 2015 in Los Angeles, California. (Photo by Frederick M. Brown/Getty Images for MTV)