A house built on a rock on the river Drina is seen near the western Serbian town of Bajina Basta, about 160km (99 miles) from the capital Belgrade May 22, 2013. The house was built in 1968 by a group of young men who decided that the rock on the river was an ideal place for a tiny shelter, according to the house's co-owner, who was among those involved in its construction. (Photo by Marko Djurica/Reuters)

Models present creations of fashion brand motonari ono during Tokyo Fantashion at a shopping district in Tokyo, Japan, August 16, 2015. Tokyo Fantashion is a one-day showcase event of up-and-coming fashion trends, organised by Tokyo Creators, a group of 20 new brands. (Photo by Yuya Shino/Reuters)

A visitor poses inside a three story upside-down family sized house at the Huashan Creative Park in Taipei, Taiwan April 7, 2016. Over 300 square meters of floor space of the upside-down house, filled with home furnishings, was created by a group of Taiwanese architects at a total cost of around US$600,000 and took 2 months to complete, according to the organisers. (Photo by Tyrone Siu/Reuters)

A spinning top is seen on a hand during a performance at Sanxia old street in New Taipei City, Taiwan May 8, 2016. Taiwan's ancient folk art of spinning tops is kept alive by a group of enthusiasts who perform intricate tricks with the toys at a temple in Taipei, the capital. (Photo by Tyrone Siu/Reuters)

Afghan paraglider Leeda Ozori, 21, walks after practicing in Kabul, Afghanistan September 14, 2015. She is one of a group of young Afghans taking to the skies of a capital where military helicopters and surveillance balloons are a far more familiar sight. Women in Afghanistan's conservative Muslim society are increasingly entering areas such as education, sports and the workplace, but most still wear the head-to-toe garment, the burqa. (Photo by Mohammad Ismail/Reuters)

A contestant of the World Beard And Mustache Championships poses for a picture during the opening ceremony of the Championships 2015 on October 3, 2015 in Leogang, Austria. Over 300 contestants in teams from across the globe have come to compete in sixteen different categories in three groups: mustache, partial beard and full beard. The event takes place every few years at different locations worldwide. (Photo by Jan Hetfleisch/Getty Images)

A biker poses on his Bousouzoku motorbike at the Dangouzaka rest stop in Yamanashi, west of Tokyo, Japan, January 3, 2016. Police on Sunday halted a group of about two dozen Bousouzoku bikers who paraded their noisy motorcycles during an annual New Year outing in the Mount Fuji region. This Japanese motorcycle subculture dated back to the 1950s and regularly chafes with the police because of their provocative traffic behaviour and bike customising, that is often deemed illegal. (Photo by Thomas Peter/Reuters)