In this task, you are given two lists A,B. Find the longest common subsequence in the lists A and B.
['i', 8549, 'h', 'd', '5915', '3671', '8841', 'n', 'l', '2933', 'l', '3719', 'w', 'r', 4949, 6965, 9729, 'q', 2999, 3943], [3137, 6813, 't', 'h', 'd', '5915', '3671', '8841', 'n', 'l', '2933', 'l', '3719', 'x', 2121]