In this task, you are given two lists A,B. Find the longest common subsequence in the lists A and B.
['u', 6097, 'J', 7797, 1503, 'R', '489', '9049', '431', 'l', 'L', '2449', 'U', 'k', 529, 8779, 1407, 'r'], ['m', 'A', 2951, 'j', 'V', 'R', '489', '9049', '431', 'l', 'L', '2449', 'x', 'm', 'B', 5559, 1921]