Paramilitary policemen take part in a training in Chaohu, Anhui province, China December 28, 2015. (Photo by Reuters/China Daily)

A child coughs as migrants and refugees run away after Macedonian police fired tear gas at hundreds of Iraqi and Syrian migrants who tried to break through the Greek border fence in Idomeni, on February 29, 2016. Greek police said more than 6,000 people were massed at the border, in a buildup triggered by Austria and Balkan states capping the numbers of migrants entering their territory. (Photo by Louisa Gouliamaki/AFP Photo)

Marieke van der Meer from the Netherlands works on her sculpture “Flora” at the sand sculpture show in Binz on Ruegen island, Germany, 09 March 2016. With the motto “Fascination Nature”, 50 sand artists have created oversized sculptures. The sculptors use 16,000 tons of special sand that is pressed into big blocks first and then formed. The 7th sand sculpture show on 5,600 square meters of exhibition ground opens on 12 March 2016. (Photo by Ens Buettner/EPA)

Spanish actor Antonio Banderas embraces a robot used in the film Automata during a photocall on the third day of the 62nd San Sebastian Film Festival, September 21, 2014. Banderas stars in and produced the science fiction film, which is part of the festival's official section. (Photo by Vincent West/Reuters)

This photographer is walking on thin ice after taking stunning photographs inside an Alaskan ice cave that could collapse at any moment. With it's dazzling turquoise walls and and huge open spaces, it's hard to imagine that this incredible frozen cavern was only formed at the beginning of 2012. But despite it's seemingly mystical allure, the fascinating natural phenomena is at risk of collapsing in on itself without warning. (Photo by Ron Gile/Caters News)

A fan of Serbia scuffles with Albania's Mergim Mavraj during their Euro 2016 Group I qualifying soccer match at the FK Partizan stadium in Belgrade October 14, 2014. The Euro 2016 qualifier between Serbia and Albania was abandoned on Tuesday following a brawl between players from both sides. (Photo by Marko Djurica/Reuters)

A resident looks into a newly-built giant trash can, partially buried underground, next to a street in Taiyuan, Shanxi province November 6, 2014. The trash can, which has a diameter of 1.9 meters and a depth of 2.8 meters, could contain approximately 10 cubic metres of garbage. It was built to replace an open-air garbage dump site, local media reported. (Photo by Reuters/Stringer)

Mariam, a 9-year-old girl, carries her brother as she stands with other children at an underground ancient cemetery in Jabal al-Zawiya in the southern countryside of Idlib November 26, 2014. Residents are using ancient caves and cemeteries as underground shelters to hide in during shelling from forces loyal to President Bashar al-Assad. Picture taken November 26, 2014. (Photo by Khalil Ashawi/Reuters)