A boy stands inside a building used as sleeping quarters at camp for refugees and migrants in Schisto, near Athens...A boy stands inside a building used as sleeping quarters at camp for refugees and migrants in Schisto, near Athens, Greece, April 26, 2016. REUTERS/Alkis Konstantinidis GREECE OUT. NO COMMERCIAL OR EDITORIAL SALES IN GREECE

Alkis Konstantinidis/Reuters

A boy stands inside a building used as sleeping quarters at camp for refugees and migrants in Schisto, near Athens, Greece

Dewdrops on plant...epa05277673 Dewdrops are seen on a leaf in Mihalygerge, 130 kms northeast from Budapest, Hungary, 26 April 2016.  EPA/Peter Komka HUNGARY OUT

Peter Komka/EPA

Dew drops are seen on a leaf in Mihalygerge, Hungary 

Water is sprayed on a tiger to keep it cool by at the Nehru Zoological park in Hyderabad, India, Tuesday, April 26, 2016. Weeks of sweltering temperatures have caused scores of deaths across India and the met department has warned that any relief from monsoon rains was still likely weeks away. (AP Photo /Mahesh Kumar A.)

Mahesh Kumar A./AP

Water is sprayed on a tiger to keep it cool by at the Nehru Zoological park in Hyderabad, India 

Syrians help a wounded youth following a...Syrians help a wounded youth following an air strike on the Fardous rebel held neighbourhood of the northern Syrian city of Aleppo on April 26, 2016.  / AFP PHOTO / AMEER ALHALBIAMEER ALHALBI/AFP/Getty Images

Ameer Alhal/AFP/Getty

Syrians help a wounded youth following an air strike on the Fardous rebel held neighbourhood of the northern Syrian city of Aleppo

Spring weather Apr 26th 2016...Rough sea at Seaham Harbour in County Durham, as snow and high winds sweep across the North East. PRESS ASSOCIATION Photo. Picture date: Tuesday April 26, 2016. Despite the approach of May, forecasters say that summer will feel a long way off. Photo credit should read: Owen Humphreys/PA Wire

Owen Humphreys/PA

Rough sea at Seaham Harbour in County Durham, as snow and high winds sweep across the North East of England

A model presents a creation from the Ronaldo Fraga collection during Sao Paulo Fashion Week show in Sao Paulo...A model presents a creation from the Ronaldo Fraga collection during Sao Paulo Fashion Week show in Sao Paulo, Brazil,

Paulo Whitaker/Reuters

A model presents a creation from the Ronaldo Fraga collection during Sao Paulo Fashion Week show in Sao Paulo, Brazil 

Inside The Beijing International Automotive Exhibition...A paramilitary police officer (right) turns around as hostesses line up for roll call ahead of the Beijing International Automotive Exhibition in Beijing, China, on Monday, April 25, 2016. Tesla Motors Inc. and BYD Co. are among manufacturers showing 147 new-energy vehicles at this year's show.

Qilai Shen/Bloomberg

A paramilitary police officer (right) turns around as hostesses line up for roll call ahead of the Beijing International Automotive Exhibition in Beijing. 

Yoga Performance At Tea Garden In Enshi...ENSHI, CHINA - APRIL 24:  (CHINA OUT) Yoga enthusiasts perform at a tea garden on April 24, 2016 in Enshi Tujia and Miao Autonomous Prefecture, Hubei Province of China.  (Photo by VCG/VCG via Getty Images)

VCG/VCG/Getty

Yoga enthusiasts perform at a tea garden in Enshi Tujia and Miao Autonomous Prefecture, Hubei Province of China

Members of the Gruppo Storico Romano (Roman Historical Group) dressed as gladiator stands at Circus Maximus as they mark the 2769th anniversary of the founding of Rome...A member of the Gruppo Storico Romano (Roman Historical Group) dressed as a gladiator stands at Circus Maximus as they mark the 2769th anniversary of the founding of Rome, Italy, April 24, 2016.   REUTERS/Alessandro Bianchi      TPX IMAGES OF THE DAY

Alessandro Bianchi/Reuters

A member of the Gruppo Storico Romano (Roman Historical Group) dressed as a gladiator stands at Circus Maximus as they mark the 2769th anniversary of the founding of Rome, Italy

Chionji Temple Recreates The Moment Of Buddhist Patriarch Death...KYOTO, JAPAN - APRIL 25:  People dressed as 25 Buddhist saints march at the Chionji temple on April 23, 2016 in Kyoto, Japan. This tri-annual ceremony which is split into three parts, a procession, a passing along of the largest prayer beads in Japan and a ritual to the cemetery to pay respects to the dead, is to commemorate the death of Honen, a patriarch of Pure Land Buddhism, recreating the moment when Honen was escorted by Amida-nyorai, the principal Buddha and 25 saints to the Pure Land at the time of his death.  (Photo by Carl Court/Getty Images)

Carl Court/Getty

People dressed as 25 Buddhist saints march at the Chionji temple in Kyoto, Japan. This tri-annual ceremony which is split into three parts, a procession, a passing along of the largest prayer beads in Japan and a ritual to the cemetery to pay respects to the dead 

US President Barack Obama visits Germany...epa05276425 German†Chancellor Angela Merkel (R) tests a Virtual Reality (VR) goggle next to US†President Barack Obama (L) as they visit the booth of ifm electronic (automation engineering) at the Hannover Messe industrial technology trade fair in Hanover,†Germany, 25 April 2016. The USA is this year's partner country at the trade fair. The US President is on a two-day visit to Germany.  EPA/CHRITSTIAN†CHARISIUS

Chritstian Charisius/EPA

German Chancellor Angela Merkel tests a Virtual Reality (VR) goggle next to US President Barack Obama as they visit the booth of ifm electronic (automation engineering) at the Hannover Messe industrial technology trade fair in Hanover, Germany

British astronaut Tim Peake in action running the London marathon while strapped to a treadmill at the International Space Station on Sunday April 24, 2016. While the official 2016 London Marathon was being run in London, Peake ran 26.2 miles on a treadmill in three hours 35 minutes 21 seconds, while aboard the apace station in orbit 250km above the Earth.(EUROPEAN SPACE AGENCY (ESA) via AP) TV OUT

ESA/AP

British astronaut Tim Peake in action running the London marathon while strapped to a treadmill at the International Space Station. While the official 2016 London Marathon was being run in London, Peake ran 26.2 miles on a treadmill in three hours 35 minutes 21 seconds, while aboard the apace station in orbit 250km above the Earth 

Ameer Alhalbi/AFP/Getty

A Syrian man evacuates an area following a reported air strike in the rebel-held neighbourhood of Hayy Aqyul in Syria‘s second city Aleppo 

Indians gather around a water tanker...epa05271987 People collect water from a water tanker, in Bhiwandi, some 60 kilometer on the outskirts of Mumbai, India, 22 April 2016. According to reports, 21 districts in Maharashtra are drought-affected. The drought, which has been ongoing for the past five months, prompted 11 states to declare a drought in 2015 and has now choked the growth of kharif (monsoon) crops, including sesame, millet and rice, for the second monsoon season in a row.  EPA/DIVYAKANT SOLANKI

Divyakant Solanki/EPA

People collect water from a water tanker, in Bhiwandi, some 60 kilometer on the outskirts of Mumbai. According to reports, 21 districts in Maharashtra are drought-affected. The drought, which has been ongoing for the past five months 

President Obama Meets With David Cameron At Downing Street...LONDON, ENGLAND - APRIL 22:  President Barack Obama arrives at Downing Street to meet with British Prime Minister David Cameron on April 22, 2016 in London, England.  The President and his wife are currently on a brief visit to the UK where they will have lunch with HM Queen Elizabeth II at Windsor Castle and dinner with Prince William and his wife Catherine, Duchess of Cambridge at Kensington Palace. Mr Obama will visit 10 Downing Street on Friday afternoon where he is to hold a joint press conference with British Prime Minister David Cameron and is expected to make his case for the UK to remain inside the European Union.  (Photo by Dan Kitwood/Getty Images)

Dan Kitwood/Getty

President Barack Obama arrives at Downing Street to meet with British Prime Minister David Cameron in London, England

Britain's Prince Philip, Duke of Edinbur...Britain's Prince Philip, Duke of Edinburgh (L) drives US President Barack Obama (2L), US First Lady Michelle Obama (2R) and Britain's Queen Elizabeth II (R) from the helicopter into Windsor Castle after the Obama's arrived for a private lunch in Windsor, southern England, on April, 22, 2016.  / AFP PHOTO / POOL / GEOFF PUGHGEOFF PUGH/AFP/Getty Images

Geoff Pugh/AFP/Getty

Britain’s Prince Philip, Duke of Edinburgh drives US President Barack Obama, US First Lady Michelle Obama and Britain’s Queen Elizabeth II from the helicopter into Windsor Castle after the Obama’s arrived for a private lunch in Windsor, southern England 

Ultra-Orthodox Jews burn leaven in the Mea Shearim neighbourhood of Jerusalem, ahead of the Jewish holiday of Passover...Ultra-Orthodox Jews burn leaven in the Mea Shearim neighbourhood of Jerusalem, ahead of the Jewish holiday of Passover, April 22, 2016. REUTERS/Ammar Awad

Ammar Awad/Reuters

Ultra-Orthodox Jews burn leaven in the Mea Shearim neighbourhood of Jerusalem, ahead of the Jewish holiday of Passover 

German Chancellor Angela Merkel attends the 500th anniversary ceremony of the German Beer Purity Law (Reinheitsgebot) in Ingolstadt, Germany, April 22, 2016.  REUTERS/Michaela Rehle

Michaela Rehle/Reuters

German Chancellor Angela Merkel attends the 500th anniversary ceremony of the German Beer Purity Law (Reinheitsgebot) in Ingolstadt, Germany

Pablo Porciuncula/AFP/Getty

A particial view of the Nyaragongo volcano taken from Goma, Democratic Republic of Congo 

Jorge Silva/Reuters

A Buddhist monk sleeps in a chair while monks and novices gather to receive alms at Wat Phra Dhammakaya temple outside Bangkok