Couples take part in a competition during a mass wedding of 64 doctoral student couples at Harbin Institute of Technology, a university in Harbin, Heilongjiang province, China, June 4, 2017. (Photo by Reuters/Stringer)

Troops of the Interior Ministry take part in a parade during a ceremony marking the Iraqi Police Day at a police academy in Baghdad January 9, 2016. (Photo by Khalid al Mousily/Reuters)

Participants take part in the annual Great Spitalfields Pancake Race in aid of London's Air Ambulance in London, Britain February 9, 2016. (Photo by Stefan Wermuth/Reuters)

A jockey drives a buffalo in the annual water buffalo race, part of a week-long festival in homage to the animals and in celebration of the rice harvest in Chonburi, Thailand on April 1, 2016. (Photo by Vichaya Pop/Barcroft Media)

A participant takes part in a zombie parade during the Brussels International Fantastic Film Festival in Brussels, Belgium, April 9, 2016. (Photo by Yves Herman/Reuters)

Iraqi security forces take part in training, as they prepare to fight against militants of the Islamic State, at a training camp on the outskirts of Mosul January 10, 2015. (Photo by Azad Lashkari/Reuters)

Indian police women take part in a full dress rehearsal for the Republic Day parade in Srinagar January 24, 2015. India will celebrate its annual Republic Day on Monday. (Photo by Danish Ismail/Reuters)

A man with a painted face and traditional costumes takes part in the Schleicherlaufen festival in the western Austrian town of Telfs February 1, 2015. (Photo by Dominic Ebenbichler/Reuters)