Artist German Vinogradov acts in the performance of the burning of installation, devoted to Maslenitsa, or Pancake Week, a pagan holiday marking the end of winter, in the village of Nikola-Lenivets, Kaluga region, Russia, February 17, 2018. (Photo by Maxim Shemetov/Reuters)

Female members of police commando march during a ceremony on International Women's Day, at the police headquarters in Islamabad, Pakistan March 8, 2018. (Photo by Faisal Mahmood/Reuters)

Members of the SubCielo company perform during the fifth annual Puerto Rico Circo Fest in San Juan, Puerto Rico, Saturday, March 10, 2018. The festival is held simultaneously in several spots on the streets of the Old San Juan city on March 10–11. (Photo by Ricardo Arduengo/AFP Photo)

South Vietnamese forces escort suspected Viet Cong officer Nguyen Van Lem (also known as Bay Lop) on a Saigon street February 1, 1968, early in the Tet Offensive. Moments later, Lem was executed by Gen. Nguyen Ngoc Loan, chief of the national police. (Photo by Eddie Adams/AP Photo)

Starlings are seen at their nesting box in a private garden in the town of Bobruisk, Belarus, April 8, 2018. (Photo by Vasily Fedosenko/Reuters)

Prince Philip, Duke of Edinburgh practicing his bicycle polo technique, Windsor Great Park, Berkshire, 1964. (Photo by Norman Potter/Daily Express/Hulton Archive/Getty Images)

A model poses with a crocodile at Chinchorro Banks, Mexico on June 21, 2018. These crocs had a lot to smile about – sporting huge toothy grins as they posed with stunning models in incredible underwater snaps. The brave models held their breath as they came face to face with the magnificent predators during the daring shoot. Photographer Ken Kiefer took a two hour boat ride to reach the carnivorous crocs at Chinchorro Banks, Mexico, along with his wife and model, Kimber and model, Melodie Trevino. (Photo by Ken Kiefer/Caters News Agency)

A woman guards stand at the gate of a cosmetic factory during a government organised visit for foreign reporters ahead of 70th anniversary of North Korea's foundation in Pyongyang, North Korea on September 8, 2018. (Photo by Danish Siddiqui/Reuters)