Internally displaced Syrian children stand at the entrance of their makeshift shelter that is an underground cave in Om al-Seer, southern Idlib countryside, Syria December 26, 2015. (Photo by Khalil Ashawi/Reuters)

Tamberly Conway, bottom left, takes part in a large snowball fight in Dupont Circle on Sunday January 24, 2016 in Washington, DC. The Washington, DC area was blanketed by a large snow event. (Photo by Matt McClain/The Washington Post)

Rihanna and Drake perform at the BRIT Awards at the O2 arena in London, Britain, February 24, 2016. (Photo by Stefan Wermuth/Reuters)

A protester jumps on the table in front of the European Central Bank President Mario Draghi during a news conference in Frankfurt, April 15, 2015. The news conference was disrupted on Wednesday when a woman in a black T-shirt jumped on the podium. (Photo by Kai Pfaffenbach/Reuters)

A pink elephant balloon, one of the entries in the Canadian Hot Air Balloon Championships, lands in a field in High River September 27, 2013. The event is a qualifier for the World Hot Air Balloon Championships in Sao Paulo in 2014. (Photo by Mike Sturk/Reuters)

A prisoner from the Pedrinhas prison is carried to receive medical help after he was injured during a fight between rival gangs inside the jail, in Sao Luiz, capital of Maranhao state, January 8, 2014. The recent posting on a major Brazilian news website of a video filmed last December 17 by Pedrinhas prisoners of the decapitated and tortured bodies of rival inmates inside the jail has highlighted some of the problems present in the country's prison system which houses nearly twice as many prisoners as its capacity, according to official statistics. (Photo by Douglas Cunha/Reuters/O Estado do Maranhão)

In this October 6, 1976 file photo a member of a Thai political faction strikes at the lifeless body of a hanged student outside Thammasat University in Bangkok October 6, 1976. For some Thais, the bloody events of October 6, 1976 are still a nightmare. On that day, heavily armed security forces shot up Bangkok's Thammasat University campus and killed scores of students, while right-wing vigilantes captured would-be escapees, subjecting them to ghoulish lynchings. (Photo by Neal Ulevich/AP Photo)

People sit on the top of a truck heavily piled with corn-stalks plies as they head for Mogadishu from Afgooye on October 19, 2016. At least four police officers were killed on October 18 when a suicide bomb attacker rammed an explosives-packed car into a police station before fighters from the Al-Qaeda-linked Shabaab group subsequently stormed the area killing at least 10 people, including soldiers and civilians. (Photo by Mohamed Abdiwahab/AFP Photo)