Revellers celebrate “Ash Monday” by participating in a colourful “flour war”, a traditional festivity marking the end of the carnival season and the start of the 40-day Lent period until the Orthodox Easter,in the port town of Galaxidi, Greece, February 27, 2017. (Photo by Alkis Konstantinidis/Reuters)

Revellers celebrate “Ash Monday” by participating in a colourful “flour war”, a traditional festivity marking the end of the carnival season and the start of the 40-day Lent period until the Orthodox Easter, in Galaxidi, Greece February 19, 2018. (Photo by Alkis Konstantinidis/Reuters)

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)

A Philippine boy collects used plastic bottles to be sold at a junk shop at Divisoria market in Manila on November 29, 2017. (Photo by Noel Celis/AFP Photo)

A U.S. Army soldier with the 10th Special Forces Group and his military working dog jump off the ramp of a CH-47 Chinook helicopter from the 160th Special Operations Aviation Regiment during water training over the Gulf of Mexico as part of exercise Emerald Warrior 2011 on March 1, 2011. (Photo by Tech. Sgt. Manuel J. Martinez/U.S. Air Force)

A young girl works at a construction site in Patiala district, Rajpura, India on November 20, 2019. (Photo by Saqib Majeed/Barcroft Media)

An Indian boy sells flowers to Hindu devotees of Lord Shiva as they perform rituals after collecting water from the river Ganges during the holy month of Shravan, In Allahabad on July 22, 2019. Shravan is considered the holiest month in the Hindu calendar with many religious festivals and ceremonies. (Photo by Sanjay Kanojia/AFP Photo)