In this task, you are given two lists A,B. Find the longest common subsequence in the lists A and B.
['B', 2419, 'n', 6163, 'h', 'J', 'U', 'u', 'O', 'o', 9979, 'P', 'A', 6161, '5851', '3847', '5281', 'f', '2039', 'C', '549', 'l', '1991', 'X', '2931', 'M', '9895', 'X', '3923', '9291', 'D', 263, 'l', 4237, 'L', 'Y', 3207, 'l', 6137, 'y'], ['l', 4639, 'G', 4127, 'D', 9621, 'r', '5851', '3847', '5281', 'f', '2039', 'C', '549', 'l', '1991', 'X', '2931', 'M', '9895', 'X', '3923', '9291', 'x', 3147, 'N', 9647, 3147]