An Acehnese female police officer wear a hijab on duty in the street in Banda Aceh, Indonesia, 27 March 2015. Indonesia National Police officially issued a regulation allowing female police officer to wear the Islamic hijab (heads craft) as a part of their uniform. Indonesia is the biggest Muslim population in the world. (Photo by Hotli Simanjuntak/EPA)

A pro-Russian rebel shows his t-shirt depicting Russian President Vladimir Putin at a checkpoint in the village of Chornukhyne near the town of Debaltseve, north-east from Donetsk, March 12, 2015. (Photo by Marko Djurica/Reuters)

A white Bengal tiger cub plays with its mother in a zoo in the Siberian city of Novosibirsk, about 2,800 kilometers (1,750 miles) east of Moscow, Russia, Tuesday, April 21, 2015. Two blue-eyed Bengal tiger cubs were born in March to a couple of white tigers at Novosibirsk zoo. (Photo by Ilnar Salakhiev/AP Photo)

14 week-old twin polar bear cubs play during their first presentation to the media in Hellabrunn zoo on March 19, 2014 in Munich, Germany. The male and female twins were born on December 9, 2013 in the zoo. (Photo by Alexandra Beier/Getty Images)

Russian Police academy female cadets march during a rehearsal for the Victory Day military parade at Dvortsovaya (Palace) Square in St Petersburg, Russia, Wednesday, May 7, 2014. Victory Day, marking the defeat of Nazi Germany, is Russia's most important secular holiday celebrated on May 9. (Photo by Dmitry Lovetsky/AP Photo)

Cars are parked near Place de la Concorde on March 12, 2014 in Paris, France. Inset: World War I, German airplanes at Place de la Concorde in Paris, wrecked by celebrating crowds on the day of the restoration of Alsace-Lorraine, November 18, 1918. (Photo by Peter Macdiarmid/Getty Images)

An actor carries a cross as he plays the role of Jesus Christ in a re-enactment of the Via Crucis (Way of the Cross) during a Holy Week procession, in preparation for Good Friday celebrations, in Luque, Paraguay, on March 27, 2013. Holy Week is celebrated in many Christian traditions during the week before Easter. (Photo by Jorge Adorno/Reuters)

A tattoo of Captain America drawn by artist Sean Karon on the leg of client Ron Raucci at the Hampton Roads Tattoo Festival in Virginia, on March 2, 2012. The tattoo was completed from start to finish in one five-and-a-half hour session and won the prestigious “tattoo of the day” contest. (Photo by Jason Reed/Reuters)