A man holds his scythe during the Harvest Festival in Hosszuheteny, Hungary, July 9, 2016. (Photo by Laszlo Balogh/Reuters)

Festival-goers enjoy on Shipyard Island, the venue of the 24th Sziget (Island) Festival in Northern Budapest, Hungary, 12 August 2016. The festival is one of the biggest cultural events of Europe presenting art exhibitions, theatrical and circus performances and music concerts. (Photo by Polyák Attila/Origo.hu)

Revellers cool themselves in the Danube River during the Sziget music festival on an island in Budapest, Hungary August 12, 2015. The event 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 Laszlo Balogh/Reuters)

A musher races with his dogs during a sled dog European Championship in Venek November 22, 2014. (Photo by Laszlo Balogh/Reuters)

General atmosphere on Shipyard Island, the venue of the 24th Sziget (Island) Festival in Northern Budapest, Hungary, 14 August 2016. (Photo by Mohai Balázs/Rockstar Photographers)

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)

A marine aims an RPG-7, a portable rocket- propelled grenade launcher, during military exercises conducted by the Russian Pacific Fleet' s naval infantry unit at the Bamburovo firing range on February 2, 2017. The drills are a part of preparations for the Suvorov Attack and Sniper Line army competitions. (Photo by Yuri Smityuk/TASS)

Soviet Army soldiers sit on their tanks in front of the Czechoslovak Radio station building in central Prague during the first day of Soviet-led invasion to then Czechoslovakia on August 21, 1968. (Photo by Libor Hajsky/Reuters)