Military vehicles surround a wreckage of a trolleybus, in Volgograd, Russia, Monday, December 30, 2013. A bomb blast tore through a trolleybus in the city of Volgograd on Monday morning, killing at least 10 people a day after a suicide bombing that killed at least 17 at the city's main railway station. Volgograd is about 650 kilometers (400 miles) northeast of Sochi, where the Olympics are to be held. (Photo by Denis Tyrin/AP Photo)

A German Air Force Officer sits astride a dead boar outside a house where he is stationed near the Western Front, in this 1918 handout picture. This picture is part of a previously unpublished set of World War One (WWI) images from a private collection. The pictures offer an unusual view of varied and contrasting aspects of the conflict, from high tech artillery to mobile pigeon lofts, and from officers partying in their headquarters to the grim reality of life and death in the trenches. The year 2014 marks the centenary of the start of the war. (Photo by Reuters/Archive of Modern Conflict London)

Jorge, an immigrant from Mexico, exits a subway station dressed as the Sesame Street character Elmo in Times Square, New York July 30, 2014. Elmo and Cookie Monster have long delighted young viewers on TV's “Sesame Street”, but the recent antics of New York street performers dressed as the beloved characters have drawn the ire of city officials and now the show's producers. Sesame Workshop, which owns the rights to Big Bird, Ernie and the assorted puppet monsters on the 45-year-old program, said on July 29, 2014 it was drafting plans to stop performers who dress up as the characters from appearing in Times Square, where they pose for photos with tourists and then demand tips. (Photo by Eduardo Munoz/Reuters)

In this photo posted on Twitter, Sunday, May 3, 2015, and provided by NASA, Italian astronaut Samantha Cristoforetti sips espresso from a cup designed for use in zero-gravity, on the International Space Station. Cristoforetti, the first Italian woman in space, fired up the first espresso machine in space, which uses small capsules, or pods, of espresso coffee. (Photo by AP Photo/NASA)

Migrants climb through the windows of a train bound for Serbia at the train station in Gevgelija, The Former Yugoslav Republic of Macedonia, 19 July 2015. Thousands of migrants who crossed Greece are on their way through Macedonia towards Serbia in order to access other European countries. Hungary in mid-July started to put up a fence on its border with Serbia, which makes the situation with the migrants in the transit countries even more complicated. The European countries on 20 July will discuss the quota of how many migrants each country should accept. (Photo by Georgi Licovski/EPA)

Blankets cover the bodies of a woman (right) and a man (left background) hit by a northbound Penn Central train (background) as they waited with a crowd at Pennsylvania Railroad station in Elizabeth, N.J. on June 8, 1968 to view the southbound train carrying the body of Sen. Robert F. Kennedy to Washington. The woman was identified as Mrs. Antoinette Severini, 54, and the man, John Curia (age unavailable), both of Elizabeth. (Photo by AP Photo)

Students salute after a man cast his vote at a polling station during the new Family Code referendum in Havana on September 25, 2022. Cubans on Sunday are voting in a landmark referendum on whether to legalize same-s*x marriage and adoption, allow surrogate pregnancies, and give greater rights to non-biological parents. (Photo by Adalberto Roque/AFP Photo)

Soldiers take a selfie on the plateform at a metro station in Ho Chi Minh City on December 22, 2024. Thousands of selfie-taking Ho Chi Minh City residents crammed into train carriages on December 22, as the traffic-clogged business hub celebrated the opening of its first-ever metro line after years of delays. (Photo by Nhac Nguyen/AFP Photo)