A man from Dinka tribe holds his AK-47 rifle in front of cows in a Dinka cattle herders camp near Rumbek, capital of the Lakes State in central South Sudan December 14, 2013. (Photo by Goran Tomasevic/Reuters)

A woman jumps as a friend (not seen) takes a photo in front of a large drawing of Pope Francis depicting him as a superhero near the Vatican January 29, 2014. The Argentinian Pope is shown taking off into air with his right fist clenched in a classic Superman style. (Photo by Alessandro Bianchi/Reuters)

A man removes ice from an ice-covered car with a hammer in Postojna, Slovenia, on February 5, 2014. Cars stand entombed in a crystal-like casing near the deserted railway station in Postojna. Trees and electricity pylons lie felled in the snow by the sheer weight of ice enveloping them. (Photo by Srdjan Zivulovic/Reuters)

This combination of April 15, 2013 and April 2, 2014 photos show a police officer clearing Boylston Street following a bomb blast near the finish line of the 2013 Boston Marathon, and pedestrians crossing at the same corner nearly a year later in Boston. (Photo by Charles Krupa/AP Photo)

Playful seals. The pair of playful seals swim around each other. Two passionate seals were captured on camera in a tender embrace by underwater photographer Robert Bailey, 50, near the Farne Islands off the Northumberland coast, UK. (Photo by Robert Bailey/Medavia)

Sunrise over Maridalsvannet in the forest areas near the outskirts of Oslo, the capital of Norway. Winter is approaching, the first snow covers the ground, and the water has already got a thin layer of ice. The temperature is significantly below the freezing point, the air is clear and the sun colors the morning clouds in deep tones. (Photo by Tore-Thiis-Fjeld/Getty Images)

Hucul horses play in the wild meadows and forests near Odrzychowa in southeastern Poland on October 18, 2014. Huculs, a primitive breed of horse, escaped total extinction due to the efforts of scientists and Polish farmers. (Photo by Janek Skarzynski/AFP Photo)

Costumed competitors run during the Marathon International du Beaujolais race near in the gardens at the castle of Pizay, November 22, 2014. Its 10th edition gathered more than 10,000 runners from 60 countries making their way on small roads, around and through the castles and vineyards, in the Beaujolais region. (Photo by Robert Pratta/Reuters)