In this task, you are given two lists A,B. Find the longest common subsequence in the lists A and B.
[1259, 7405, 'k', 'Q', '3929', '9671', '1539', 'k', 'd', 'P', 'x'], ['W', 'B', 797, 'o', 'Q', '3929', '9671', '1539', 'f', 6955, 9773, 7]