Residents observe a police officer take up position during an operation at the Mare slums complex in Rio de Janeiro March 25, 2014. The federal troops have taken control of security operations in Mare slums complex to help quell a surge in violent crime following attacks by drug traffickers on police posts in three slums on the north side of the city, government officials said. (Photo by Ricardo Moraes/Reuters)

A woman crowd-surfs in front of the main stage at the Woodstock Festival in Kostrzyn-upon-Odra, close to the Polish-German border, August 2, 2014. Some 500 thousand people attended the festival that is the brainchild of Polish journalist and social campaigner Jerzy Owsiak. He initiated the event to say thank you to those who donated money to his GOCC charity organisation that delivers medical care for children. (Photo by Thomas Peter/Reuters)

This July 2014 image provided by the Bureau of Land Management shows the interior of the Natural Trap Cave in north-central Wyoming. The cave holds the remains of tens of thousands of animals, including many now-extinct species, from the late Pleistocene period tens of thousands of years ago. Scientists have resumed digging for the first time in more than 30 years. (Photo by AP Photo/Bureau of Land Management)

Indian policemen keep guard from the window of a residential house during curfew in Srinagar, Indian controlled Kashmir, Wednesday, July 13, 2016. Curfew imposed in the disputed Himalayan region continues for the fifth consecutive day to suppress anti-India violence following the Friday killing of Burhan Wani, chief of operations of Hizbul Mujahideen, Kashmir's largest rebel group. (Photo by Mukhtar Khan/AP Photo)

Women pose for a selfie at Ipanema Beach in Rio de Janeiro, Brazil on July 30, 2016. (Photo by Nacho Doce/Reuters)

Hindu devotees take part in the religious festival of Holi, also known as the festival of colours, in the town of Barsana in the Uttar Pradesh region of India, March 16, 2016. (Photo by Cathal McNaughton/Reuters)

Members of the general public enjoy the “BEACH” at the National Building Museum August 25, 2015 in Washington, DC. The “BEACH” is an interactive architectural installation, with an “ocean” of nearly one million recyclable translucent plastic balls, that brings the experience of going to the beach indoor. (Photo by Alex Wong/Getty Images)

Sri Lankan flood victims flock around a bus to receive food parcels on a inundated road in Colombo, Sri Lanka, Tuesday, May 17, 2016. The Disaster Management Center said that 114 homes have been destroyed and more than 137,000 people have been evacuated to safe locations as heavy rains continue. (Photo by Eranga Jayawardena/AP Photo)