Indian women in traditional dress take part in a tug of war during the Suwori festival in Boko about 75 kilometers (47 miles) west of Gauhati, India, Monday, April 20, 2015. Traditional elephant fights, elephant races, tug of war and dances mark this festival which coincides with the Assamese Rongali Bihu, or the harvest festival of the northeastern Indian state of Assam. (Photo by Anupam Nath/AP Photo)

An opponent of Maricopa County Sheriff Joe Arpaio, Jorge Mendez, of Glendale, Ariz., wears an Arpaio mask as he sits on a toilet while protesting in front of U.S. District Court Tuesday, April 21, 2015, in Phoenix. Arpaio is in a federal courtroom starting for a four-day trial to decide whether he should be held in contempt of court for ignoring a judge's orders and destroying and withholding evidence in a racial-profiling lawsuit. (Photo by Ross D. Franklin/AP Photo)

Smoke and lava spew from the Villarrica volcano, as seen from Pucon town, in the south of Santiago, April 22, 2015. Authorities have restricted access to the area within 5 kilometres (3 miles) of the crater and have put the area under an orange alert due to the volcano's heightened unrest and increased likelihood of eruption. (Photo by Cristobal Saavedra/Reuters)

Mount Sinabung is seen during an eruption from Surbakti village in Karo, North Sumatra, Indonesia, April 20, 2015. The local government is preparing the relocation of residents from three of the villages that were destroyed. (Photo by Tibta Pangin/Getty Images/Anadolu Agency)

In this image provided by NASA/JSC, astronauts Steven L. Smith and John M. Grunsfeld are photographed during an extravehicular activity (EVA) during the December 1999 Hubble servicing mission of STS-103, flown by Discovery. The Hubble Space Telescope, one of NASA'S crowning glories, marks its 25th anniversary on Friday, April 24, 2015. With more than 1 million observations, including those of the farthest and oldest galaxies ever beholden by humanity, no man-made satellite has touched as many minds or hearts as Hubble. (Photo by NASA/JSC via AP Photo)

School children from Belgium sit on a tank on display as they listen to an Israeli soldier speaks about Israel's wars, near the wall of names of fallen soldiers, at the Armored Corps memorial, before a ceremony marking the annual Memorial Day for soldiers and civilians killed in more than a century of conflict between Jews and Arabs, in Latrun near Jerusalem, Israel, Wednesday, April 22, 2015. Israel came to a standstill on Wednesday as sirens wailed across the country on its annual Memorial Day for fallen soldiers and victims of terrorism. (Photo by Ariel Schalit/AP Photo)

An ambulance goes up in flames after it was set fire by angry villagers at a government hospital in Siwan, about 200 kilometers (125 miles) north of Patna, Bihar state, India, Monday, April 20, 2015. Villagers who took injured students of a road accident to this hospital became incensed when they discovered no doctors were present. About 100 people attacked the hospital in anger and burned six vehicles, including this ambulance. (Photo by Abhinav Patel/AP Photo)

Chilean dancers from Temuco walk in Larcomar shopping mall in the Miraflores district of Lima April 17, 2015. The dancers are in Lima to participate in an event to promote the Copa America soccer championship to be held in Chile in June 2015. (Photo by Mariana Bazo/Reuters)

Japan's Prime Minister Shinzo Abe (C) poses with members of Japanese idol group Momoiro Clover Z and other show-business celebrities at a cherry blossom viewing party at Shinjuku Gyoen park in Tokyo April 18, 2015. Thousands of people including entertainers, athletes and politicians were invited to the annual party hosted by Abe. (Photo by Issei Kato/Reuters)

Japan's Prime Minister Shinzo Abe (C) poses with members of Japanese idol group Nogizaka46 and other kimono-clad show-business celebrities at a cherry blossom viewing party at Shinjuku Gyoen park in Tokyo April 18, 2015. (Photo by Issei Kato/Reuters)

Japan's Prime Minister Shinzo Abe (front R) talks with members of Japanese idol group Momoiro Clover Z at a cherry blossom viewing party at Shinjuku Gyoen park in Tokyo April 18, 2015. (Photo by Issei Kato/Reuters)

Japan's Prime Minister Shinzo Abe (R) greets guests during a cherry blossom viewing party at Shinjuku Gyoen park in Tokyo April 18, 2015. (Photo by Issei Kato/Reuters)

Japan's Prime Minister Shinzo Abe (C) poses with members of Japanese idol group Momoiro Clover Z and other show-business celebrities at a cherry blossom viewing party at Shinjuku Gyoen park in Tokyo April 18, 2015. (Photo by Issei Kato/Reuters)

A man who lives on selling usable items found in a dumpsite, preaches to fellow workers on the outskirts of Tegucigalpa April 17, 2015. At the dumpsite people scavenge through the garbage looking for usable items like plastic, metals and cardboard to sell and recycle, making some 100 Lempiras ($4.80) per day, according to local media. (Photo by Jorge Cabrera/Reuters)

A man looks for usable items in a dumpsite on the outskirts of Tegucigalpa April 17, 2015. (Photo by Jorge Cabrera/Reuters)

Tokuo Fukuichi, executive vice president of Lexus, poses next to a Lexus LF-NX mid-size crossover concept during a media preview day at the Frankfurt Motor Show (IAA) in this September 10, 2013 file photo. Big may be beautiful, but Toyota Motor Corp's global design chief is betting that edgy is the way to go for the Japanese automaker's premium Lexus brand, specifically its signature “spindle grille” design. Fukuichi, who is also Lexus' global chief, says the design shock-therapy gives the brand – and conservative Toyota more broadly – the stand-out face it previously lacked. (Photo by Ralph Orlowski/Reuters)

Chevrolet's FNR electric self-driving concept is seen during a presentation at an event ahead of the 16th Shanghai International Automobile Industry Exhibition in Shanghai, April 19, 2015. (Photo by Aly Song/Reuters)

People run for cover after an explosion in Jalalabad April 18, 2015. A suicide bomb blast in Afghanistan's eastern city of Jalalabad killed 33 people and injured more than 100 outside a bank where government workers collect salaries, the city's police chief said on Saturday. Police were also investigating if there was a second explosion after people rushed to the scene to help, and said that a third blast that shook Jalalabad was a controlled detonation after experts discovered another bomb close to the scene of the first explosion. (Photo by Reuters/Parwiz)

Policemen keep watch at a site after a third explosion in Jalalabad April 18, 2015. (Photo by Reuters/Parwiz)

A man carries an injured boy after a suicide attack in Jalalabad April 18, 2015. The suicide bomb blast in Afghanistan's eastern city of Jalalabad killed 33 people and injured more than 100 outside a bank where government workers collect salaries, the city's police chief said on Saturday. Police were also investigating if there was a second explosion after people rushed to the scene to help, and said that a third blast was a controlled detonation after experts discovered another bomb close to the scene of the first explosion. (Photo by Reuters/Pajwak News Agency)

An Afghan woman walks at the site of a suicide attack in Jalalabad April 18, 2015. The suicide bomb blast in Afghanistan's eastern city of Jalalabad killed 33 people and injured more than 100 outside a bank where government workers collect salaries, the city's police chief said on Saturday. (Photo by Reuters/Parwiz)

A worker sews Tunisian national flags in a workshop in Tunis April 17, 2015. Picture taken April 17, 2015. (Photo by Zoubeir Souissi/Reuters)

Olga Govortsova of Belarus has her leg massaged in a break during her FedCup World Group II play-off tennis match against Kurumi Nara of Japan in Tokyo April 18, 2015. Seated at R is Belarus captain Tatiana Poutchek. (Photo by Thomas Peter/Reuters)

Kashmiri protesters throw stones towards Indian policemen during a daylong protest strike in Narbal, north of Srinagar April 18, 2015. One person died on Saturday in Kashmir following an injury suffered after police opened fire to disperse stone-throwing demonstrators during a daylong protest strike over the arrest of a separatist leader. Police said around 24 people were injured in the clashes, and one of the three people injured after they opened fire died in hospital. (Photo by Danish Ismail/Reuters)

Relatives mourn next to the body of a Kashmiri youth, who died in a clash between Kashmiri protesters and police during a daylong protest strike in Narbal, north of Srinagar April 18, 2015. (Photo by Danish Ismail/Reuters)

An Indian policeman (C) is being helped by colleagues after he was injured in a clash with Kashmiri protesters during a daylong protest strike in Narbal, north of Srinagar April 18, 2015. (Photo by Danish Ismail/Reuters)

A Kashmiri woman wails and runs towards the site of a protest after receiving news of her husband's injury during a protest in Narbal, some 15 Kilometers (10 miles) North of Srinagar, Indian controlled Kashmir, Saturday, April 18, 2015. Government forces fired on anti-India protesters Saturday and killed a teenage student on the second day of violent clashes in the disputed Himalayan region, police said. Relatives disputed the official account, saying the boy was killed in custody. (Photo by Dar Yasin/AP Photo)

A migrant is helped as she disembarks from a Coast Guard boat in the Sicilian harbour of Palermo April 18, 2015. (Photo by Guglielmo Mangiapane/Reuters)

A family member of Aan Kaji Sherpa, one of the 16 Nepali Sherpa guides who were killed during an avalanche last year, offers prayer in memory of Aan Kaji at a monastery in Kathmandu April 18, 2015. More than 4,000 climbers have reached the summit of Everest, the world's highest peak, since it was first scaled by Sir Edmund Hillary and Tenzing Norgay Sherpa in 1953. In April 2014, an avalanche killed 16 Nepali Sherpa guides who were fixing ropes and ferrying supplies for their foreign clients to climb the 8,850-metre (29,035-foot) peak. The accident – the deadliest in the history of Mount Everest – triggered a dispute between sherpa guides who wanted a climbing ban in honour of their colleagues and the Nepali government that refused to close the mountain. The sherpas staged a boycott, forcing hundreds of foreign climbers to call off their bids to climb Everest. (Photo by Navesh Chitrakar/Reuters)

Daughters of Aan Kaji Sherpa, one of the 16 Nepali Sherpa guides who were killed during an avalanche last year, light butter lamps in memory of their father at a monastery in Kathmandu April 18, 2015. (Photo by Navesh Chitrakar/Reuters)

A man offers flower in front of the portraits of 16 Nepali Sherpa guides, who were killed during an avalanche last year, during an event organised in memory of the Sherpas in Kathmandu April 18, 2015. (Photo by Navesh Chitrakar/Reuters)

Daughters of Aan Kaji Sherpa, one of the 16 Nepali Sherpa guides who were killed during an avalanche last year, light butter lamps in memory of their father at a monastery in Kathmandu April 18, 2015. (Photo by Navesh Chitrakar/Reuters)

Monks performs religious rituals in memory of Aan Kaji Sherpa, one of the 16 Nepali Sherpa guides who were killed during an avalanche last year, at a monastery in Kathmandu April 18, 2015. (Photo by Navesh Chitrakar/Reuters)

A man lights butter lamp in front of the portraits of 16 Nepali Sherpa guides, who were killed during an avalanche last year, during an event organised in memory of the Sherpas in Kathmandu April 18, 2015. (Photo by Navesh Chitrakar/Reuters)

The three daughters of Ang Kaji Sherpa, one of the 16 sherpas who died in the Everest Avalanche one year ago, pray during a memorial organised in the Lhundrup Choeling monastery for the memory of their father on April 18, 2015 in Kathmandu, Nepal. (Photo by Omar Havana/Getty Images)

Displaced Somali girls carry water for domestic use at a camp on the outskirts of Bosasso in Somalia's Puntland April 18, 2015. (Photo by Feisal Omar/Reuters)

A staff talks to a humanoid robot named Han developed by Hanson Robotics via a mobile phone during the Global Sources spring electronics show in Hong Kong April 18, 2015. According to Hanson Robotics the robot's skin is made out of a material called Frubber, an elastic polymer that mimics the human skin, and installed with about 40 motors on its face which help create various expressions. Han can answer simple questions and staff said it can be used in the field of customer service. (Photo by Tyrone Siu/Reuters)

A humanoid robot named Han developed by Hanson Robotics reacts as the controller commands it via a mobile phone to make a facial expression during the Global Sources spring electronics show in Hong Kong April 18, 2015. (Photo by Tyrone Siu/Reuters)

A humanoid robot named Han developed by Hanson Robotics reacts as the controller commands it via a mobile phone to make a facial expression during the Global Sources spring electronics show in Hong Kong April 18, 2015. (Photo by Tyrone Siu/Reuters)

A humanoid robot named Han developed by Hanson Robotics reacts as the controller commands it via a mobile phone to make a facial expression during the Global Sources spring electronics show in Hong Kong April 18, 2015. (Photo by Tyrone Siu/Reuters)

A staff controls the expressions of a humanoid robot named Han developed by Hanson Robotics via a mobile phone during the Global Sources spring electronics show in Hong Kong April 18, 2015. (Photo by Tyrone Siu/Reuters)

Taliban insurgents stand over three men, accused of murdering a couple during a robbery, before shooting them during their execution in Ghazni Province April 18, 2015. The Taliban announced the execution of the three men accused of murdering a couple during a robbery, saying they had been tried by an Islamic court. The killing was carried out in front of a crowd by Taliban fighters who fired at the men with AK-47s, according to a Reuters witness. Footage seen by Reuters show the men were made to sit on the ground with their eyes blindfolded and their hands tied at the time of their execution. (Photo by Reuters/Stringer)

A member of the Taliban fires his rifle during the execution of three men accused of murdering a couple during a robbery in Ghazni Province April 18, 2015. (Photo by Reuters/Stringer)

A member of the Taliban fires his rifle during the execution of three men accused of murdering a couple during a robbery in Ghazni Province April 18, 2015. (Photo by Reuters/Stringer)

Participants in the Tweed Run ride their bicycles over Westminster Bridge in central London April 18, 2015. The Tweed Run is an annual event in which the participants wear vintage clothing and ride their bicycles though city centres worldwide. (Photo by Suzanne Plunkett/Reuters)

A participant models his moustache in Trafalgar Square at the start of the Tween Run in central London April 18, 2015. (Photo by Suzanne Plunkett/Reuters)

Norway's Prime Minister Erna Solberg (C) dances with Hmong pupils at Lao Chai primary school as she visits ethnic Hmong communities in Vietnam's northern Sapa district April 18, 2015. (Photo by Reuters/Kham)

Men hold a woman on a snowboard as they pose for a picture after finishing a “downhill ski and snowboard descent in swimwear” event on Mount Zelyonaya (The Green Mount), at a ski resort near the town of Sheregesh in the Siberian Kemerovo region April 18, 2015. Organisers said that more than 1,600 snowboarders and skiers from Barnaul, Kemerovo, Krasnoyarsk, Novosibirsk, Novokuznetsk and other Siberian cities turned up for the event, hitting the slopes of Mount Zelyonaya in their swimwear in an attempt to update a Guiness World Record, as part of the annual “Grelka” ski festival. (Photo by Ilya Naymushin/Reuters)

Snowboarders and skiers take part in a “downhill ski and snowboard descent in swimwear” event on Mount Zelyonaya (The Green Mount), at a ski resort near the town of Sheregesh in the Siberian Kemerovo region April 18, 2015. (Photo by Ilya Naymushin/Reuters)

People walk next to historic picture taken in May 1945 which is part of an open air exhibition to mark the end of World War Two in front of the Brandenburg Gate in Berlin April 18, 2015. The world marks the 70th anniversary of the end of World War Two on May 9, 2015. (Photo by Fabrizio Bensch/Reuters)

Abraham Lincoln impersonators take photos of Mary Todd Lincoln impersonators during the Association of Lincoln Presenters Annual Convention at the Vandalia Statehouse in Vandalia, Illinois April 18, 2015. Reenactors representing both President Abraham Lincoln and his wife, Mary Todd Lincoln, gathered in Vandalia from across the country in an annual event which celebrates the life of the 16th president of the United States. (Photo by Whitney Curtis/Reuters)

A man walks past graffiti in Athens April 19, 2015. Greece aims for a deal with its creditors over a reforms package but will not retreat from its red lines, the country's deputy prime minister told the Sunday newspaper To Vima, not ruling out a referendum or early polls if talks reach an impasse. (Photo by Alkis Konstantinidis/Reuters)