Two boys look out from the Mangueira slum towards the Maracana Stadium that is hosting the Rio's 2016 Summer Olympics opening ceremonies, in Rio de Janeiro, Brazil, Friday, August 5, 2016. (Photo by Leo Correa/AP Photo)

A sofa floats in the polluted waters of Jacarepagua Lagoon, during a press tour in Rio de Janeiro, March 9, 2015. A press tour was organised by biologist Mario Moscatelli, to call attention to pollution on the waters of the lagoons which surround the Rio 2016 Olympic Park. (Photo by Ricardo Moraes/Reuters)

Children play in an outdoor shower as a soldier takes part in a surprise operation in the Manguinhos slum in Rio de Janeiro, Brazil, Thursday, January 18, 2018. Troops have been sent to Rio due to the increase of the violence, and in an attempt to help restore order, but so far have had little impact. The operation on Thursday took place three weeks ahead of Carnival, when thousands of tourists are expected to arrive in the city. (Photo by Leo Correa/AP Photo)

Soldiers stand guard in Maua square where a cotton candy vendor passes by in Rio de Janeiro, Brazil, Saturday, July 9, 2016, as security is deployed to get to know the areas they'll be patrolling during the Olympics. Roughly twice the security contingent at the London Olympics will be deployed during the August games in Rio, which are expected to draw thousands of foreigners to a city where armed muggings, stray bullets and turf wars between heavily armed drug gangs are routine. (Photo by Leo Correa/AP Photo)

Larissa Neto, a muse of the Unidos da Tijuca Samba School, poses as she wears a carnival dress in Sao Goncalo near Rio de Janeiro, Brazil, February 3, 2016. Rio de Janeiro's carnival parades are known the world over for the glitz and glamour, high-tech allegorical floats and shimmering bodies, which battle it out each year for the championship title. Each school is fronted by the Queen of the Drums, who dances alongside the raging percussion, and her court of sparkling, sculpted dancers known as “muses”. (Photo by Ricardo Moraes/Reuters)

Members of the Uniao da Ilha do Governador Samba School perform during the first day of the Special Group Samba Schools parade of Carnival at the Sambadrome in Rio de Janeiro, Brazil, 07 February 2016. (Photo by Luiz Eduardo Perez/EPA)

Carnival revellers pose during the postponed “Rosenmontag” (Rose Monday) parade in Mainz, Germany, May 8, 2016, after the original parade in February was cancelled due to severe weather. (Photo by Ralph Orlowski/Reuters)

A man wearing a native costume named “Woman Carrying Husband” poses ahead of the Carnival in Sostanj January 15, 2015. Slovenians and members of various ethnological groups celebrate the annual carnival, also known locally as Pust, by wearing traditional masks and costumes to symbolically “chase away” the winter. Prust runs from February 7 to 17 this year. (Photo by Srdjan Zivulovic/Reuters)