In this task, you are given two lists A,B. Find the longest common subsequence in the lists A and B.
['O', 6439, 'O', 'a', '5223', 'Z', 'D', 'c', '5241', 'Y', '9033', 'k', 2121], [5697, 'a', 9669, 'a', '5223', 'Z', 'D', 'c', '5241', 'Y', '9033', 'X', 't']