Members of the New People's Army (NPA) female guerrillas perform a cultural show during the release of a Philippines army soldier in Sugbongcogon town, Misamis Oriental, southern Philippines, November 20, 2015. NPA spokesperson Allan Juanito warned that they will seize more soldiers to exchange them with the government as "Prisoners of war". (Photo by Froilan Gallardo/Reuters)

Elementary school children play outside their classrooms as mount Sinabung volcano spews thick volcanic ash in the background on February 10, 2017 in Karo, Indonesia. Mount Sinabung is one of the most active volcanoes in Indonesia and last erupted in May 2016, killing seven people. (Photo by Albert Damanik/Barcroft Images)

The sculpture “It Takes Two to Tango” by Scottish sculptor David Mach is seen in front of the headquarters of the CMA-CGM shipping company office tower in the port of Marseille, France, March 15, 2016. (Photo by Jean-Paul Pelissier/Reuters)

Joshua Patino stands on a ladder to put finishing touches on a giant dinosaur exhibit at PAX East in the Boston Convention and Expo Center, Thursday, April 21, 2016, in Boston. PAX East, an annual celebration of gaming culture, is expected to draw tens of thousands of visitors Friday through Sunday. It's a place where serious gamers can preview unreleased video games and devices, compete in tournaments, hear live music and meet others for whom gaming is a way of life. (Photo by Elise Amendola/AP Photo)

A woman directs traffic in the pouring rain in Pyongyang, North Korea on May 3, 2016. The city is preparing for the Workers' Party Congress starting on May 6th. It will be the first time since 1980 that the ruling party has convened. (Photo by Linda Davidson/The Washington Post)

Flying pigeons pass over Nepalese street vendors near the earthquake damaged UNESCO World Heritage Site, Durbar Square in Kathmandu on May 20, 2015. Nearly 8,500 people have now been confirmed dead in the disaster, which destroyed more than half a million homes and left huge numbers of people without shelter with just weeks to go until the monsoon rains. (Photo by Ishara S. Kodikara/AFP Photo)

Visitors crowd an artificial wave swimming pool at a tourist resort to escape the summer heat in Daying county of Suining, Sichuan province, China, July 11, 2015. (Photo by Reuters/Stringer)

Russia's synchronised swimming duet Aleksandr Maltsev (L) and Darina Valitova compete in the Mixed Duet Technical preliminary during the synchronised swimming competition at the 2015 FINA World Championships in Kazan on July 25, 2015. (Photo by Christophe Simon/AFP Photo)