KYIV, Ukraine — Fighting against Russia’s 4-year-old invasion has cost the lives of 55,000 Ukrainian soldiers, according to Ukraine’s President Volodymyr Zelenskyy, as a U.S. envoy described two days of talks between Moscow and Kyiv officials as “detailed and productive.” Ukraine has also listed “a large number of people" as missing in the war, Zelenskyy added in an interview broadcast by French TV channel France 2 late Wednesday. The last time the Ukrainian leader gave a figure for battlefield