Ukrainian President Volodymyr Zelensky, French President Emmanuel Macron, Russian President Vladimir Putin and German Chancellor Angela Merkel (L to R) attend "Normandy four summit" in Paris, France, Dec. 9, 2019. Ukraine and Russia agreed on a full and comprehensive implementation of the ceasefire in eastern Ukraine before the end of 2019, leaders of Russia, Ukraine, France and Germany announced in Paris on Monday evening following their talks called "Normandy four summit". (Xinhua/Gao Jing)?