In this task, you are given two lists A,B. Find the longest common subsequence in the lists A and B.
['i', 4251, 8671, 'y', 'U', 'n', 'P', 'Y', '2729', 'j', 3775, 'M', 5689], ['y', 6173, 'U', 'n', 'P', 'Y', '2729', 'a', 633]