In this task, you are given two lists A,B. Find the longest common subsequence in the lists A and B.
[4669, 8067, 'u', 'b', '5839', '4369', 'p', 'M', 'L', 'J'], [5807, 1929, 'Q', 'b', '5839', '4369', 'p', 'x', 'x', 417, 855]