Migrants climb through the windows of a train bound for Serbia at the train station in Gevgelija, The Former Yugoslav Republic of Macedonia, 19 July 2015. Thousands of migrants who crossed Greece are on their way through Macedonia towards Serbia in order to access other European countries. Hungary in mid-July started to put up a fence on its border with Serbia, which makes the situation with the migrants in the transit countries even more complicated. The European countries on 20 July will discuss the quota of how many migrants each country should accept. (Photo by Georgi Licovski/EPA)

Blankets cover the bodies of a woman (right) and a man (left background) hit by a northbound Penn Central train (background) as they waited with a crowd at Pennsylvania Railroad station in Elizabeth, N.J. on June 8, 1968 to view the southbound train carrying the body of Sen. Robert F. Kennedy to Washington. The woman was identified as Mrs. Antoinette Severini, 54, and the man, John Curia (age unavailable), both of Elizabeth. (Photo by AP Photo)

A Hong Kong Correctional Services Dog Unit (CSDU) officer demonstrates training at the CSDU training facility in Stanley, Hong Kong, China, 27 February 2018. The Hong Kong CSDU consists of 29 staff members divided across six dog teams. According to the department's latest figure from 2017, the average daily penal population of Hong Kong was 8,529. (Photo by Jérôme Favre/EPA/EFE)

Myanmar T-72 battle tank competes in an individual race of the Tank Biathlon competition as part of the 7th International Army Games 2021 at the Alabino training ground, Moscow region, Russia, 27 August 2021. The 7th International Military-Technical Forum “Army-2021” is held from 22 August till 04 September 2021 at 23 military training grounds of 11 countries. Five thousand participants of 277 teams from 42 countries compete in 34 military contests. (Photo by Sergei Ilnitsky/EPA/EFE)

A member of Kyrgyzstan's first female hockey team arrives for a training session in the village of Otradnoye, Kyrgyzstan on February 4, 2020. Based in the remote village of Otradnoe, 249 miles (400 kilometres) east of the country's capital Bishkek, the team comprises of around 15 girls from a local school and uses a flooded allotment to train on during the winter months. (Photo by Vladimir Pirogov/Reuters)

A student attending a winter military camp reacts during a training session in Ansan, south of Seoul January 3, 2013. Hundreds of students between 11 and 17 years old attend winter boot camp training courses every year. The winter courses range from 4 to 14 days at the Blue Dragon Camp run by retired marines, which also offers summer boot camp for students. (Photo by Kim Hong-Ji/Reuters)

Afghan air force 2nd Lt. Niloofar Rhmani walks the flight line at Shindand Air Base, Afghanistan, prior to her graduation from undergraduate pilot training, on May 13, 2013. Rhmani made history on May 14, when she became the first female to successfully complete undergraduate pilot training and earn the status of pilot in more than 30 years. She will continue her service as she joins the Kabul Air Wing as a Cessna 208 pilot. (Photo by Senior Airman Scott Saldukas/USAF)

Rescue specialists for USA-1 drill through a concrete slab to rescue a victim from the scene of a mock disaster area during a training exercise at the Guardian Center in Perry, Georgia, March 25, 2014. A week of field training, the first of its kind at the 830-acre training site, to be open to the media, began Monday with the arrival of USA-1 from Fairfax, Virginia along with its sister team in Los Angeles, California. USA-1 has been deployed by the U.S. Agency for International Development to 30 foreign disasters, including earthquakes in Haiti, Armenia and Iran, the tsunami in Japan and the typhoon in the Philippines. (Photo by Shannon Stapleton/Reuters)