A woman is supported by two men while crossing a river, north of Idomeni, Greece, as migrants attempt to reach Macedonia on a route that would bypass the border fence, Monday, March 14, 2016. Hundreds of migrants and refugees walked out of an overcrowded camp on the Greek-Macedonian border Monday, determined to use a dangerous crossing to head north. (Photo by Vadim Ghirda/AP Photo)

Nova Scotia Duck Tolling retriever Torrey competes in the 10th annual Petco Unleashed surfing dog contest at Imperial Beach, California August 1, 2015. Proceeds raised at the event go to benefit the San Diego Humane Society. (Photo by Mike Blake/Reuters)

Cats gather in front of a house damaged by shelling in the town of Dokuchayevsk, south of Donetsk, February 12, 2015. (Photo by Maxim Shemetov/Reuters)

“Show us our butts! Mucawana tribe – Angola. In Soba village, the Muhacaona (Mucawana) tribe, perhaps the best place i have visited. They use cow dung and fat to make this so nice haircut, and love the beads. They asked me to make pictures of their backs... and butts to see on the camera screen if everything was perfect!”. (Photo and comments by Eric Lafforgue)

A mine detection rat is given banana as a reward after successfully identifying an inactive mine on July 2, 2015 in Siem Reap, Cambodia. The Cambodian Mine Action Center (CMAC) working with the Belgian NGO APOPO has recently begun testing the feasability of using large mine detection rats from Tanzania to help clear fields of mines and unexploded ordnance in one of the most bombed and mined countries in the world. (Photo by Taylor Weidman/Getty Images)

Military school cadets take part in a ceremony commemorating the 56th anniversary of the death of Camilo Cienfuegos who, along with Fidel Castro and Che Guevara, was a chief commander of the Cuban revolution in Havana, Cuba on October 28, 2015. (Photo by Xinhua/REX Shutterstock)

Armed Yemeni children sit in the back of a pick up truck with fighters loyal to Yemen's Saudi-backed President Abedrabbo Mansour Hadi in the Dar saad neighbourhood of the southern Yemeni city of Aden on May 10, 2015, as they continue to battle Shiite Huthi rebels. (Photo by Saleh Al-Obeidi/AFP Photo)

A Swiss police officer accompanies a migrant from Syria carrying her baby, upon her arrival at the railway station in the north-eastern Swiss town of Buchs September 1, 2015. (Photo by Arnd Wiegmann/Reuters)