In this task, you are given two lists A,B. Find the longest common subsequence in the lists A and B.
['m', 3213, 5485, 1285, 'x', 'U', '371', '9941', 'q', '6563', 'g', '7295', 'B', 3475], ['u', 5391, 'A', 1763, 8983, 'x', 'U', '371', '9941', 'q', '6563', 'g', '7295', 'x', 'S']