People enjoy the sunny weather on the Smetovi mountain range near Zenica, Bosnia and Herzegovina, December 20, 2015. REUTERS/Dado Ruvic

A woman walks on the Smetovi mountain range near Zenica, Bosnia and Herzegovina, December 20, 2015. REUTERS/Dado Ruvic TPX IMAGES OF THE DAY

A woman takes a picture with a smartphone on the Smetovi mountain range near Zenica, Bosnia and Herzegovina, December 20, 2015. REUTERS/Dado Ruvic

A tree stands near fog over the central Bosnian town of Vitez on the Lisac mountain range during sunset November 17, 2013. REUTERS/Dado Ruvic (BOSNIA AND HERZEGOVINA - Tags: SOCIETY ENVIRONMENT)

A view shows the Grlo bridge over river Moraca in central Montenegro, June 23, 2013. Fifteen people were killed and 31 injured when a passenger bus with Romanian licence plates fell into a deep river gorge in central Montenegro on Sunday, officials said. REUTERS/Stevo Vasiljevic (MONTENEGRO - Tags: DISASTER TRANSPORT TPX IMAGES OF THE DAY)

A house built on a rock on the river Drina is seen near the western Serbian town of Bajina Basta, about 160km (99 miles) from the capital Belgrade May 22, 2013. The house was built in 1968 by a group of young men who decided that the rock on the river was an ideal place for a tiny shelter, according to the house's co-owner, who was among those involved in its construction. REUTERS/Marko Djurica (SERBIA - Tags: ENVIRONMENT SOCIETY TRAVEL TPX IMAGES OF THE DAY)

A girl sits on Smetovi mountain as she watches the sunset over the central Bosnian town Zenica November 18, 2012. The city of Zenica, one of the most polluted cities in Bosnia and Herzegovina and the Balkan peninsula, is suffocating on a daily basis, with one of the biggest polluters being a steel factory that is located only a few miles away from the city centre. REUTERS/Dado Ruvic (BOSNIA AND HERZEGOVINA - Tags: ENVIRONMENT SOCIETY)

Girls jump into the lake in Podpec near Ljubljana, August 6, 2012. Picture taken with a wide angle lens. REUTERS/Srdjan Zivulovic (SLOVENIA - Tags: SOCIETY ENVIRONMENT)

Seats are seen on a chair lift on the skiing slope in Kranjska gora December 14, 2011. Skiing season will start after Christmas in Slovenia due to the lack of snow at skiing centres.
REUTERS/Srdjan Zivulovic (SLOVENIA - Tags: ENVIRONMENT)

A man takes photos of the sunset and fog over the central Bosnian town of Zenica on the Smetovi mountain range, November 29, 2011. REUTERS/Dado Ruvic (BOSNIA AND HERZEGOVINA - Tags: ENVIRONMENT)

A swan swims in Lake Bled with Bled island in the background August 26 , 2011. REUTERS/Srdjan Zivulovic (SLOVENIA - Tags: SOCIETY ANIMALS TRAVEL)

A church on Bled island and a castle are seen on Lake Bled August 26 , 2011. REUTERS/Srdjan Zivulovic (SLOVENIA - Tags: SOCIETY TRAVEL)

Girls make their way to church for their horses to be blessed by priests on St. Stephens day in Srednja Vas December 26, 2009. REUTERS/Srdjan Zivulovic (SLOVENIA - Tags: ANIMALS SOCIETY RELIGION)

A Bosnian villager cuts grass in front of remnants of ancient settlements near the village of Umoljani, perched some 1,300 metres (4265 feet) up on the rocky southern ridges of Mount Bjelasnica July 3, 2007. Life in Umoljani is deeply connected to the traditional pursuits of farming and sheep breeding. A warm welcome, handmade artefacts and organic food are a window into the past, but also a hit with tourists looking for a different sort of holiday. Picture taken July 3, 2007. To match feature BOSNIA-TOURISM/ REUTERS/Danilo Krstanovic (BOSNIA AND HERZEGOVINA)

Five sport yachts sail on the vast Lake Ohrid that spans the Macedonian-Albanian border May 26, 2005. Picture taken May 26, 2005. REUTERS/Hazir Reka HR/AA

Albanian boys tend sheep in the Kosovo mountain village of Devetak, some 80 kilometres east of the capital Pristina, September 7, 2004. REUTERS/Hazir Reka NO RIGHTS CLEARANCES OR PERMISSIONS ARE REQUIRED FOR THIS IMAGE HR/WS