In this task, you are given two lists A,B. Find the longest common subsequence in the lists A and B.
['f', 'L', 'k', '9117', '4243', '4931', 'i', 'I', 'M', 'B', 'z', 'q', 7463], [3593, 'U', 'E', 'I', 'g', 6981, 'k', '9117', '4243', '4931', 'i', 'I', 'O', 9877, 5643, 'r', 1223]