Retired Malam Jabba engineer Akbar Ali skis down the piste at the ski resort in Malam Jabba, Pakistan February 7, 2017. Atop the piste of Malam Jabba in Pakistan's once dangerous Swat Valley skiers schuss downhill, a new Chinese-built chairlift ferries tourists to the peak, and a luxury hotel is under construction to replace one torched by the Taliban. (Photo by Caren Firouz/Reuters)

Irene Bowker, 88 years old at the Punk Rebellion festival at The Winter Gardens, talks to a woman with a tatooed head and mohican haircut in Blackpool, Lancashire, UK on August 6, 2015. A clash cultures at the famous seaside town of Blackpool as punks attending the annual Rebellion festival at the Winter Gardens come shoulder to shoulder with traditional holidaymakers. (Photo by MediaWorldImages/Alamy Stock Photo)

A recruitment drive during the First World War at Trafalgar Square, London. (Photo by Central Press/Getty Images)

The summit of one of Europe's tallest mountains glows like the flame of a candle as the sun rises on a clear morning. The Matterhorn, famous for appearing on bars of Toblerone chocolate bars, reflects the vivid orange light at 5.37am. (Photo by Margarethe Jaeger/Solent News & Photo Agency)

Participants lay down on a street covered by coloured powder during the annual Bangkok Color Run in Bangkok, Thailand April 1, 2017. (Photo by Athit Perawongmetha/Reuters)

The Flying Bull's P-38 Lockheed Lightning N25Y / 13 – Red Bull – Flying Legends Airshow 2012 Duxford (Photo by Rob Lovesey)

A man takes a selfie in front of a fire from oil that has been set ablaze in the Qayyarah area, some 60 kilometres (35 miles) south of Mosul, on October 19, 2016, during an operation by Iraqi forces against Islamic State (IS) group jihadists to retake the main hub city. In the biggest Iraqi military operation in years, forces have retaken dozens of villages, mostly south and east of Mosul, and are planning multiple assaults for October 20. (Photo by Yasin Akgul/AFP Photo)

Two people sit in an ambulance waiting to be treated after a Grad rocket slammed into a shopping mall in Donetsk's Kubishevski district, in the eastern Ukraine, on October 8, 2014. At least two people were killed, and five were injured after some six Grad rockets hit the area. (Photo by John Macdougall/AFP Photo)