Russian Prime Minister Dmitry Medvedev (R, center) and Bulgarian Prime Minister Boyko Borissov (L, center) walk before the Tomb of the Unkown Soldier in Sofia, capital of Bulgaria, March 4, 2019. Bulgaria and Russia here on Monday during a visit of Russian Prime Minister Dmitry Medvedev expressed their willingness to further develop bilateral ties on the basis of traditional friendship and a wide range of opportunities. (Xinhua/Zhan Xiaoyi)