Secondary school graduates play in a fountain as they celebrate the last day of school, traditionally called the “last bell” in central Kiev, Ukraine on May 31, 2019. (Photo by Valentyn Ogirenko/Reuters)

A Ukrainian serviceman fires a 2S7 Pion self-propelled gun during military exercises near the village of Divychky in Kiev region, Ukraine, October 21, 2016. (Photo by Valentyn Ogirenko/Reuters)

First graders of a cadet's lyceum attend a ceremony to mark the start of the new school year in Kiev, Ukraine, September 1, 2015. September 1 marks the start of a new academic year for students in Ukraine.(Photo by Valentyn Ogirenko/Reuters)

Members of the Territorial Defence Forces and volunteers place anti-tank obstacles at a checkpoint, as Russia's invasion of Ukraine continues, at the Independence Square in central Kyiv, Ukraine on March 3, 2022. (Photo by Valentyn Ogirenko/Reuters)

Secondary school graduates play in a fountain as they celebrate the last day of school, traditionally called the “last bell” in central Kiev, Ukraine on May 31, 2019. (Photo by Valentyn Ogirenko/Reuters)

People dressed in traditional costumes sing Christmas carols as they gather to celebrate Orthodox Christmas at a compound of the National Architecture museum in Kyiv, Ukraine on January 7, 2022. (Photo by Valentyn Ogirenko/Reuters)

Ukrainian serviceman Valerii looks on at a position in a frontline, amid Russia's attack on Ukraine, in Mykolaiv region, Ukraine on October 26, 2022. (Photo by Valentyn Ogirenko/Reuters)

A security personnel plays with a girl in the compound of a health and rest centre which serves as a temporary accommodation for refugees from eastern regions of the country in the town of Korostyshiv, Zhytomyr region, Ukraine, July 30, 2015. More than 400 people who left eastern Ukraine due to a military conflict have arrived at the sanatorium in Korostyshiv since the summer of 2014, according to representatives. (Photo by Valentyn Ogirenko/Reuters)