Russian pop art photographer Sergey Chilikov captures a nation liberated from the social oppression of late-era Soviet rule – at parties, in the streets, and bouncing high. His exhibition, Photoprovocations, will be at Photo London, 19-22 May. Here: Yoshkar-Ola, Matrosova Street (1995). (Photo by Sergey Chilikov)

Images created with Post-it notes are seen in the windows of offices at 75 Varick Street in lower Manhattan, New York, U.S., May 18, 2016, where advertising agencies and other companies have started what is being called a “Post-it note art war” with employees creating colorful images in their windows with Post-it notes. (Photo by Mike Segar/Reuters)

Salvadoran clown Cosquilla poses for a picture during the VIII Central America Clown Convention in San Salvador, El Salvador, May 18, 2016. (Photo by Jose Cabezas/Reuters)

(L-R) Barbara Palvin, Bella Hadid and Izabel Goulart appear on stage at the amfAR's 23rd Cinema Against AIDS Gala at Hotel du Cap-Eden-Roc on May 19, 2016 in Cap d'Antibes, France. (Photo by Andreas Rentz/Getty Images)

A man from the Ogiek community harvests honey in Mount Elgon game reserve, where they have reached an agreement with the government allowing them to remain in their ancestral lands in western Kenya, April 26, 2016. (Photo by Katy Migiro/Reuters)

Unidentified relatives and friends of passengers who were flying in an EgyptAir plane that vanished from radar en route from Paris to Cairo react as they wait outside the Egyptair in-flight service building where relatives are being held at Cairo International Airport, Egypt May 19, 2016. (Photo by Amr Abdallah Dalsh/Reuters)

Tribesmen loyal to the Houthi movement perform the Baraa dance during a gathering to show support to the movement in Sanaa, Yemen, May 19, 2016. Bara or Baraa dance is one of the several traditional outdoor dances performed by men in the country of Yemen. Bara dance literally means a dagger dance, where each dancer holds a dagger. The style of the Bara dance differs from tribe to tribe. It is performed on special occasions. (Photo by Khaled Abdullah/Reuters)

An officer reviews members of the honor guard as they line up before a welcoming ceremony for visiting Mozambique's President Filipe Jacinto Nyusi at the Great Hall of the People in Beijing, Wednesday, May 18, 2016. (Photo by Mark Schiefelbein/AP Photo)