Pope Francis greets the crowd from his popemobile in downtown Rio de Janeiro. Pope Francis touched down in Rio de Janeiro on Monday, starting his first foreign trip as pontiff and a weeklong series of events expected to attract more than a million people to a gathering of young faithful in Brazil, home to the world's largest Roman Catholic population. (Photo by Ueslei Marcelino/Reuters)

Young man making the O.K. sign. (Photo by George Marks/Retrofile/Getty Images). Circa 1950s

Members of the Times Square Alliance snow clearing team take a photo on a snowbank at Times Square in the Manhattan borough of New York January 23, 2016. A winter storm dumped nearly 2 feet (58 cm) of snow on the suburbs of Washington, D.C., on Saturday before moving on to Philadelphia and New York, paralyzing road, rail and airline travel along the U.S. East Coast. (Photo by Shannon Stapleton/Reuters)

A dancer dressed for the annual procession honoring San Pedro, his town's patron saint, runs through the street of San Pedro Sacatepequez near Guatemala City June 29, 2016. (Photo by Saul Martinez/Reuters)

A federal agent removes mud from a house damaged by a mudslide in Xaltepec, Mexico, Monday, August 8, 2016. Mountain communities in two Mexican states are recovering from weekend mudslides that killed dozens during heavy rains brought by remnants of Hurricane Earl. (Photo by Pablo Spencer/AP Photo)

Bronze medalist Carlos Coloma Nicolas of Spain celebrates after finishing third in the cross-country cycling mountain bike race at the 2016 Summer Olympics in Rio de Janeiro, Brazil, Saturday, August 20, 2016. (Photo by Patrick Semansky/AP Photo)

Attendees arrive dressed as their favourite comic characters for the MCM London Comic Con, a convention to celebrate the culture of comic books and related art forms, in London, Britain, May 25, 2018. (Photo by Toby Melville/Reuters)