In this task, you are given two lists A,B. Find the longest common subsequence in the lists A and B.
['x', 'b', 9957, 'k', 505, '8309', 'z', '8961', '851', '3811', 'N', 'u', 1875, 1521], ['F', 'B', 9607, 'o', '8309', 'z', '8961', '851', '3811', 'N', 'G', 'z']