For modern Poland, the answer is rather simple. Russian, and later Soviet soldiers, were stationed inside the Polish borders for almost the whole 19th and 20th centuries (with a notable exception for interwar period Poland (minus 1920)). The last Soviet soldier left Poland on September 18, 1993 (some kind of symbolic date taking into consideration that Soviet aggression started on September 17).
But... what about eighteenth century?
Can we say that Russian troops were here for 250 years or rather 300 years?