In this task, you are given two lists A,B. Find the longest common subsequence in the lists A and B.
['L', 2457, 'O', 4791, '3033', '6169', '311', '5771', 'K', 6647, 'x'], [1755, 'u', 'S', '3033', '6169', '311', '5771', 'u', 'M', 'L']