A new volunteer for the Ukrainian interior ministry's “Azov” battalion takes part in tests before heading to frontlines in eastern Ukraine, at the battalion's training centre in Kiev, Ukraine, August 14, 2015. (Photo by Gleb Garanich/Reuters)

Couples take part in the “Love and Challenge Marathon” in Hanoi, Vietnam, 16 August 2015. Fifty couples, who are going to get married, participated in the event which is held the fifth time. This year, the winners of the marathon received a honeymoon trip to Malaysia. (Photo by Luong Thai Linh/EPA)

Russian President Vladimir Putin (R) looks through a window of a research bathyscaphe while submerging into the waters of the Black Sea as he takes part in an expedition near Sevastopol, Crimea, August 18, 2015. (Photo by Alexei Nikolsky/Reuters/RIA Novosti/Kremlin)

A police officer gives instructions to migrants rushing to board a train that would take them towards Serbia, at the railway station in the southern Macedonian town of Gevgelija, Wednesday, August 20, 2015. Macedonian police stepped up the security at the border with Greece apparently trying to stem recent surge of migrants who are coming from Greece. (Photo by Darko Vojinovic/AP Photo)

A historical re-enactor poses for a photograph in a living history camp as he prepares to take part in an anniversary event for the Battle of Bosworth near Market Bosworth in central Britain August 22, 2015. The Battle of Bosworth took place in 1485 during the War of the Roses between the Houses of Lancaster and the House of York. King Richard III was defeated by Henry Tudor marking the end of Plantagenet rule and the beginning of the Tudor dynasty. (Photo by Neil Hall/Reuters)

Indian Hindu devotees wait to take part in an event to mark Pongal in Mumbai on January 15, 2016. Pongal, which coincides with the Hindu festival Makara Sankranthi, is a thanksgiving and harvest celebrated throughout India and specifically by those from the Indian state of Tamil Nadu. (Photo by Indranil Mukherjee/AFP Photo)

A passenger takes off his pants as others not wearing pants dance while waiting for a subway train during the “No Pants Subway Ride” in Mexico City, Mexico, February 21, 2016. The event is an annual flash mob and occurs in different cities around the world, according to its organisers. (Photo by Carlos Jasso/Reuters)

A picture taken with slow shutter speed shows members of the group “The Kattfiller” from Attendorn taking part during the Norddeutsche Championship carnivalesque dance sport in Kassel (Hessen), Germany, 28 February 2016. About 1,100 qualified dancers show in different disciplines their skills. (Photo by Swen Pfoertner/EPA)