In this task, you are given two lists A,B. Find the longest common subsequence in the lists A and B.
[3643, 1725, 'P', '3709', '6405', 'm', 'O', 'd', 'N', 7157, 3267, 't', 'i'], [2461, 519, 's', 'x', '3709', '6405', 'm', 'O', 'd', 'm', 2521, 'Q']