Jan Kara (R) and Jan Holan pedal their boat, made with plastic bottles, on the Elbe river near Kostelec nad Labem July 15, 2014. Jan Kara, a 22-year-old student, and Jakub Bures, a 22-year-old car mechanic, built the 10-metre (32.8-feet) long boat from 5000 plastic bottles strapped to a wooden frame. (Photo by David W. Cerny/Reuters)

Bangladeshi railway police try to clear line, as thousands of Bangladeshi Muslims gather to board trains to return home after attending three-day Islamic Congregation on the banks of the River Turag in Tongi, 20 kilometers (13 miles) north of the capital Dhaka, Bangladesh, Sunday, January 26, 2014. (Photo by A. M. Ahad/AP Photo)

In this January 27, 2014 photo, snow rollers dot a lot at the northwest corner of Olive and North Main streets in Akron, Ohio. The snow balls are formed naturally when high winds push snow across a hill. (Photo by Michael Chritton/AP Photo/Akron Beacon Journal)

A large storm cloud covers the Sydney CBD on March 5, 2014 in Sydney, Australia. A severe thunderstorm warning was issued for the Sydney metropolitan area late this afternoon with heavy rainfall due to cause flash flooding in areas. (Photo by Cassie Trotter/Getty Images)

An anti-government protester wearing a Guy Fawkes mask stands with a shield near flames from molotov cocktails thrown at a water cannon by anti-government protesters during riots in Caracas in this April 20, 2014 file photo. (Photo by Jorge Silva/Reuters)

An aerial view of a livestock enclosure of the Himba people, in October, 2014, in the Namib Desert, Namibia. A photographer has captured a bird's eye view of the stunning Namib Desert from a paraglider. Theo Allofs travels the world taking stunning pictures of untouched landscapes from a unique perspective. Soaring 300 metres above ground, Theo shot the yellow sand dunes, dry red river beds and remote townships in Namibia. (Photo by Theo Allofs/Barcroft Media)

A man carries an injured girl after what activists said were five air strikes by forces loyal to Syria's President Bashar al-Assad in Douma, eastern al-Ghouta, near Damascus September 11, 2014. (Photo by Bassam Khabieh/Reuters)

Urszula Sidoruk, 19, from the paramilitary group SJS Strzelec (Shooters Association), trains her workout at a gym in Siedlce, eastern Poland March 18, 2014. Inspired by the war in Ukraine, growing numbers of Poles are joining volunteer paramilitary groups, where they receive basic army training and prepare to defend their homeland. (Photo by Kacper Pempel/Reuters)