Men wear masks as they sit in the metro in Prague, Czech Republic, 17 March 2020. According to media reports, the Czech government decided to impose a two-week quarantine in the country on the evening of 15 March, and ban all international travel from 16 March 2020. Currently 383 cases of the coronavirus SARS-CoV-2, which causes the Covid-19 disease, have been officially confirmed in Czech Republic. (Photo by Martin Divisek/EPA/EFE)

Over 30 Douglas C-47 Skytrains (Dakotas) making final preparations for flight formation practice before the 75th D-Day Anniversary flight to Normandy in Duxford, England on June 4, 2019. (Photo by UK Air Force Images)

A man smashes an apple with a sword placed on the head of a man wearing a knave costume during the Easter knight event on April 21, 2014 in Berlin. The easter knight event delivers an insight into medieval lifestyle. (Photo by Rainer Jensen/AFP Photo/DPA)

Mariam, a 9-year-old girl, carries her brother as she stands with other children at an underground ancient cemetery in Jabal al-Zawiya in the southern countryside of Idlib November 26, 2014. Residents are using ancient caves and cemeteries as underground shelters to hide in during shelling from forces loyal to President Bashar al-Assad. Picture taken November 26, 2014. (Photo by Khalil Ashawi/Reuters)

A workman walks past a large mural on the side of a building during the “Sand Sea & Spray” Urban Art Festival in Blackpool, north west England on July 11, 2015. (Photo by Oli Scarff/AFP Photo)

An officer wipes sweat off the face of a Chinese People's Liberation Army (PLA) honor guard soldier as they rehearse for a welcoming ceremony for New Zealand's Governor-General Sir Jerry Mateparae at the Great Hall of the People in Beijing, Tuesday, July 21, 2015. (Photo by Mark Schiefelbein/AP Photo)

Radio City Music Hall Rockettes perform after days of rehearsal and routine polished to perfection at the Radio City Music Hall in New York City on July 26, 1949. (Photo by Ivan Dmitri/Getty Images)

Medics carry an injured at the explosion site in the busy center of Turkish capital, Ankara, Turkey, Sunday, March 13, 2016. The explosion is believed to have been caused by a car bomb that went off close to bus stops. News reports say the large explosion in the capital has caused several deaths and many casualties. (Photo by AP Photo)