Men rest after salvaging metal on the 30th floor of the “Tower of David” skyscraper in Caracas February 3, 2014. A 45-storey skyscraper in the center of Venezuela's capital Caracas is a slum, probably the highest in the world. Dubbed the “Tower of David”, the building was intended to be a shining new financial center but was abandoned around 1994 after the death of its developer – banker and horse-breeder David Brillembourg – and the collapse of the financial sector. (Photo by Jorge Silva/Reuters)

A worker walks through a salt pan on the eve of May Day or Labour Day on the outskirts of the southern Indian city of Chennai April 30, 2014. India is the third largest salt producing country in the world after China and U.S. with global annual production about 230 million tonnes, according to government data. (Photo by Reuters/Babu)

A Brazilian drug gang member nicknamed Pilintra, 26, poses with a gun atop a hill overlooking a slum in Salvador, Bahia State, April 11, 2013. One of Brazil's main tourist destinations and a 2014 World Cup host city, Salvador suffers from an unprecedented wave of violence with an increase of over 250% in the murder rate, according to the Brazilian Center for Latin American Studies (CEBELA). (Photo by Lunae Parracho/Reuters)

Mexicans dressed as French soldiers carry handcrafted guns, ahead of a reenactment of the battle of Puebla between Zacapoaxtla Indians and the French army during Cinco de Mayo celebrations in Mexico City, Tuesday, May 5, 2015. Monsalvo said he has been portraying Napoleon III in the annual neighborhood event for 28 years. Cinco de Mayo commemorates the victory of an ill-equipped Mexican army over French troops in Puebla on May 5, 1862. (Photo by Rebecca Blackwell/AP Photo)

Spanish runner Francisco Contreras, 77, known as “Super Paco”, runs as he participates in the XVIII 101km international competition in the outskirts of Ronda, southern Spain, May 9, 2015. About 7,000 participants, including runners, mountain bikers and duathletes, run a track of 101 km (63 miles) in less than 24 hours through the “Serrania de Ronda” (Ronda Mountain Range) during this competition organised by the 4th Tercio (Regiment) “Alejandro Farnesio” of the Spanish Legion. The Puente Nuevo is 120 metres (394 feet) high over the gorge of the river that divides the city of Ronda. Picture taken using long exposure. (Photo by Jon Nazca/Reuters)

People carry the body of a man they uncovered from under the rubble of houses destroyed by Saudi airstrikes in the old city of Sanaa, Yemen, Friday, June 12, 2015. (AP Photo/Hani Mohammed)

A man poses for a photo with a life size cutout of Pope Francis at Bicentennial Park where the pontiff celebrated Mass for an estimated half-million people, in Quito, Ecuador, Tuesday, July 7, 2015. Francis told an estimated half-million people gathered for the Mass that in a world divide by wars, violence and individualism, Catholics should be “builders of unity”, bringing together hopes and ideals of their people. (Photo by Ana Buitron/AP Photo)

Residents make their way along a fence as they try to cross a flooded street after heavy rainfall hit Wuhan, Hubei province, China, July 23, 2015. Severe downpours hit the city on Thursday, flooding streets and shutting down public transportations, local media reported. (Photo by Reuters/China Daily)