North Korean commuters are seen through a door window waiting to board a train in a subway train station in Pyongyang, North Korea, 14 April 2017. North Koreans are preparing to celebrate the “Day of the Sun” festival, commemorating the 105th birthday anniversary of former supreme leader Kim Il-sung on 15 April, as tension over nuclear issues rise in the region. (Photo by How Hwee Young/EPA)

Italian Air Force's aerobatic demonstration team, the Frecce Tricolori leave colourful vapour trails as they fly over the Altare della Patria monument on Republic Day (Festa della Repubblica) in Rome, Italy, 02 Jun 2017. The anniversary marks the founding of the Italian Republic in 1946. (Photo by Massimo Percossi/EPA)

Gremio fans celebrate after their team won the Copa Libertadores final match at the Arena do Gremio in Porto Alegre, Brazil on November 29, 2017. (Photo by Diego Vara/Reuters)

This picture taken on October 20, 2016 shows students practising wushu at the Tagou martial arts school in Dengfeng. China is investing hugely in football training and has vowed to have 50 million school- age players by 2020, as the ruling Communist party eyes “football superpower” status by 2050. (Photo by Nicolas Asfouri/AFP Photo)

Children walk past the partially collapsed boundary wall of a school and a Buddhist shrine that were damaged during the earthquake earlier this year at Khumjung, a typical Sherpa village in Solukhumbu district also known as the Everest region, in this picture taken November 30, 2015. (Photo by Navesh Chitrakar/Reuters)

A timber truck driver (L) dressed as Father Frost is saluted by a soldier at the Kremlin's Spasskiye (Saviour) Gate in Moscow, Russian Federation, on December 24, 2013. (Photo by Vyacheslav Prokofyev/ITAR-TASS/ZUMA Press)

A stuffed rabbit doll sits among children's beds standing in the abandoned kindergarten of Kopachi village located inside the Chernobyl Exclusion Zone on September 29, 2015 near Chornobyl, Ukraine. Kopachi, a village that before 1986 had a population of 1,114, lies only a few kilometers south of the former Chernobyl nuclear power plant, where in 1986 workers inadvertantly caused reactor number four to explode, creating the worst nuclear accident in history. (Photo by Sean Gallup/Getty Images)

A reveller dressed up as Austrian drag queen and 2014 Eurovision song contest winner Conchita Wurst takes part in New Year's celebrations in Coin, near Malaga, southern Spain, early January 1, 2015. Villagers and revellers dressed up in funny costumes to take part in the New Year's celebration. (Photo by Jon Nazca/Reuters)