Students from St Andrews University indulge in a tradition of covering themselves with foam to honour the “academic family” on the lower college lawn on October 23, 2017, in St Andrews, Scotland. (Photo by Jeff J. Mitchell/Getty Images)

U.S. President Donald Trump boards Air Force One to depart for Vietnam from Beijing Airport in Beijing, China on November 10, 2017. (Photo by Jonathan Ernst/Reuters)

Eurovision fans from Sweden kiss in front of the Globen Arena prior the first the Eurovision Song Contest final in Stockholm, Sweden, Saturday, May 14, 2016. (Photo by Martin Meissner/AP Photo)

Local residents fight to collect free drinking water from municipal corporation tanker on a hot summer day on the outskirts of Ahmedabad, India June 1, 2016. (Photo by Amit Dave/Reuters)

F/A-18 fighter jet takes off from the USS Harry S. Truman aircraft carrier in the eastern Mediterranean Sea June 13, 2016. (Photo by Baz Ratner/Reuters)

Bavarian herdsmen and a herdswoman in traditional dresses drive their beasts on a road during the return of the cattle from the summer pastures in the mountains near Oberstaufen, Germany, Friday, September 9, 2016. (Photo by Matthias Schrader/AP Photo)

Models pose in creations from the Salinas collection during Sao Paulo Fashion Week in Sao Paulo, Brazil, Wednesday, April 25, 2018. (Photo by Andre Penner/AP Photo)

View of the Villarrica volcano taken from Pucon, some 800 kilometres south of Santiago, showing signs of activity on December 06, 2017. (Photo by Christian Miranda/AFP Photo)