An armed youth loyal to the Houthi movement takes part in a protest against the Saudi-backed exiled government deciding to cut off the Yemeni central bank from the outside world, in the capital Sanaa, Yemen August 25, 2016. (Photo by Mohamed al-Sayaghi/Reuters)

A hot air balloon in tortoise shape flies in the air during the Tazaungdaing air balloon festival in Pyin Oo Lwin, Myanmar, 25 November 2015. During the festival, hot air balloons made of multicolored papers and hung with paper lanterns, fireworks and fire sticks are exploded in mid-air. (Photo by Hein Htet/EPA)

People stroll alongside one of the hills of the Tio Pio park in Madrid, Monday, January 25, 2016. The park is a high viewpoint frequented mostly by locals due to its view of the Spanish capital skyline. (Photo by Francisco Seco/AP Photo)

A pilot looks up from a U.S. F-22 Raptor fighter as it prepares to refuel in mid-air with a KC-135 refuelling plane over European airspace during a flight to Britain from Mihail Kogalniceanu air base in Romania April 25, 2016. (Photo by Toby Melville/Reuters)

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)

Firefighters pull a pig as they try to rescue it from a well at a pig farm in Huanghua township of Leqing, Zhejiang province, April 25, 2014. Seven local firefighters successfully rescued a 300 kg (661 lbs) pig which fell down a well on Friday morning, local media reported. (Photo by Reuters/China Daily)

A Honduras fan cheers for her team before the start of the Group E football match between Honduras and Switzerland at the Amazonia Arena in Manaus during the 2014 FIFA World Cup on June 25, 2014. (Photo by Rodrigo Arangua/AFP Photo)

A hairdressing mannequin is seen outside a hair salon amid as Typhoon Matmo hits Nantong, Jiangsu province July 25, 2014. Matmo, which made landfall in Fujian Province on Wednesday, has brought strong winds and heavy downpours to more areas in China after it moved northward on Thursday, Xinhua News Agency reported. (Photo by Reuters/Stringer)