Members of the opening committee enter the dance floor at the Opera Ball in Vienna February 27, 2014. The 18 to 24-year-olds spend weeks rehearsing for a performance that lasts just three or four minutes but has a huge audience at home and abroad. Tickets for the ball start at 250 euros ($340) and a box costs as much as 18,500 euros ($25,000). REUTERS/Leonhard Foeger (AUSTRIA - Tags: ENTERTAINMENT)