Guests arrive for the opening ceremony of the 23rd Life Ball in Vienna May 16, 2015. Life Ball is Europe's largest annual AIDS charity event and takes place in Vienna's city hall. The Life Ball is a charity gala to raise money for people living with HIV and AIDS. (Photo by Leonhard Foeger/Reuters)

A debutante from a local academy looks at her mobile phone as she waits to take part in the Vienna Ball at the Kempinski Hotel, March 19, 2016, in Beijing. The ball, which is an event organized by the luxury Kempinski Hotel chain and the City of Vienna, brings together both Chinese and foreign members of the capital's elite class. Despite a slowing economy, private wealth has soared in China after decades of rapid growth. A record number of high net worth individuals and families has fuelled a market for luxury goods, services, and events catering to China's burgeoning elite class. (Photo by Kevin Frayer/Getty Images)

A white lipizzaner Stallion performs during the Spanish Riding School of Vienna Gala Performance at Wembley Arena on November 24, 2011 in London, England. (Photo by Chris Jackson/Getty Images)

Model Yasmine Petty arrives on the Life Ball plane on May 15, 2015 in Vienna, Austria. The Life Ball, an annual charity ball raising funds for HIV & AIDS projects, will take place on May 16, 2015 at the city hall in Vienna. (Photo by Monika Fellner/Getty Images)

The rising sun illuminates the sky above the spires of a church in Vienna, Austria, November 17, 2015. (Photo by Heinz-Peter Bader/Reuters)

A jogger runs on the bank of Donaukanal channel in central Vienna, Austria, September 5, 2016. (Photo by Heinz-Peter Bader/Reuters)

A snail (Helix Aspersa) and a baby snail sit on a leave in a farm in Vienna June 12, 2013. Andreas Gugumuck owns Vienna's largest snail farm, exporting snails, snail-caviar and snail-liver all over the world. The gourmet snails are processed using old traditional cooking techniques and some are sold locally to Austrian gourmet restaurants. (Photo by Leonhard Foeger/Reuters)

Street musicians with their faces covered with animal masks play to earn some money in central Vienna, Austria, November 8, 2015. (Photo by Vasily Fedosenko/Reuters)