A sofa floats in the polluted waters of Jacarepagua Lagoon, during a press tour in Rio de Janeiro, March 9, 2015. A press tour was organised by biologist Mario Moscatelli, to call attention to pollution on the waters of the lagoons which surround the Rio 2016 Olympic Park. (Photo by Ricardo Moraes/Reuters)

View at one of the sculptures by Swiss artist H.R. Giger during the opening of the Ars Electronica 2013 exhibition “HR Giger. The Art of Biomechanics” in Linz, Austria, 04 September 2013. (Photo by EPA/RUBRA)

The giant mural titled “Under the Hand” by Maclaim Crew is visible on a building facade in Kreuzberg district on June 26, 2014 in Berlin, Germany. Berlin, with its long tradition of counter-culture, has become a mecca for street art of all dimensions and messages. (Photo by Sean Gallup/Getty Images)

Completion is near on Monaco's tallest skyscraper ever, and its first new one since the 1980s. Fueled by a luxury-housing boom in the tax-haven nation, the Odeon Tower's so-called Sky Penthouse is expected to sell for more than any other apartment in the world has ever sold before. Photo: The five-story Sky Penthouse is expected to be complete in September 2015. The water slide extends from a dance floor in the residence down to a private infinity pool. (Photo by Tour Odeon)

First graders attend a festive ceremony to mark the start of another school year in Slaviansk, September 1, 2014. September 1 marks the start of a new academic year for students in Ukraine. (Photo by Gleb Garanich/Reuters)

A Palestinian youth jumps with a sword as he demonstrates his ninja-style skills for the photographer in front of the ruins of buildings, that were destroyed in 2014 war, in the northern Gaza Strip January 29, 2016. The youths, who have been receiving martial arts training at local clubs in Gaza for the past two years, decided to form a team to hold regular shows in the hope that the publicity generated will eventually lead to them being invited to participate in international contests. (Photo by Mohammed Salem/Reuters)

An Israeli soldier prays in front of a tank at a military staging area near the border with the Gaza Strip, in this July 24, 2014 file photo. Israel's long-running struggle to balance modern standards with Jewish tradition has come to a head in the military, where new orders curtailing beards among soldiers have met protests from some rabbis. (Photo by Nir Elias/Reuters)