In this task, you are given two lists A,B. Find the longest common subsequence in the lists A and B.
['U', 'd', 5387, 'C', 'w', '157', '6331', '5261', 'o', 'y', 'c', '2791', 'U', 5237, 'i', 9143, 'h'], [8491, 'w', 7817, '157', '6331', '5261', 'o', 'y', 'c', '2791', 'x', 'n', 'g', 'f', 6023, 7843, 4401]