In this task, you are given two lists A,B. Find the longest common subsequence in the lists A and B.
['u', 5181, 'e', 'Q', '7123', 'g', 'L', '3841', 'k', 'A', 'B', 'a', 'U'], ['O', 9321, 3431, '7123', 'g', 'L', '3841', 'k', 'A', 'B', 'U', 7581, 'b', 6497, 'z']