Sergey, one of the participants of PARTISAN courses, poses for a portrait in an abandoned building in Olgino, St. Petersburg, Russia on November 23, 2016. Sergey came to St. Petersburg from the city of Cheliabinsk to attend an intensive seven-day program. Sergey is a businessman, a traveller and a blogger. His another passion are “men's hobbies”, that's why he participated in the paramilitary courses. (Photo by Alexander Aksakov/The Washington Post)

Participants of the techno-parade “Zug der Liebe” (Train of love) dance on a street in Berlin, Germany July 25, 2015. The “Zug der Liebe” is the successor to the “Loveparade”, which in its heyday attracted up to 100,000 participants and ended in disaster and tragedy in 2010 when 21 people died and over 500 were injured due to suffocation from overcrowding at the “Loveparade” in Duisburg. (Photo by Axel Schmidt/Reuters)

Participants climb a 10km muddy obstacle course during the “Run Mud” race, on March 29, 2019 in the Israeli mediterranean coastal city of Tel Aviv. Over 6,000 participants took part in the obstacle race, with up to 18 artificial obstacles on three tracks (10 km, five km or two km). (Photo by Jack Guez/AFP Photo)

Participants learn how to survive in the wild, including tips on how to make it through a zombie invastion at a “Zombie First Responder” course March 11, 2012 in Sandy, Oregon. In an intensive 2-day curriculum participants train in everything from wilderness and urban survival, nerf or nerd weaponry, stealth and evasion, and proper zombie “disposal”. (Photo by Natalie Behring/Getty Images)

Participants take part in the Color Run near the Eiffel Tower in Paris April 19, 2015. The Color Run is a five-kilometre race, held in cities across the U.S. and also worldwide, with the aim of promoting healthy living and to benefit a charity that organizers choose in each of the cities that the run visits. Participants are doused from head to toe in different colors at each kilometre. (Photo by Benoit Tessier/Reuters)

Participants perform during a Latin dance competition in Tel Aviv, Israel July 18, 2015. Some 66 dancers took part in the contest on Saturday, selecting a winning couple to represent Israel in the finals of The World Latin Dance Cup, which will be held at the end of the year in Miami. (Photo by Amir Cohen/Reuters)

Pashtan Wagner, a Blue Oriental Cat participates in the GCCF Supreme Cat Show at National Exhibition Centre on October 28, 2017 in Birmingham, England. (Photo by Shirlaine Forrest/WireImage)

Participants wearing fantasy costumes attend the 4th Hero Festival in Marseille, France on November 11, 2017. The 4th Hero Festival edition has attracted all sorts of people to role play their favourite characters from all kinds of movies and comic book legends. (Photo by Jean-Paul Pelissier/Reuters)