In this task, you are given two lists A,B. Find the longest common subsequence in the lists A and B.
['D', 7121, 7235, 7121, 'R', 't', 'P', 'i', '545', 'l', 'q', 'P', 'f', 'F', '6923', '9257', '9417', 'r', 'a', 6027, 3327, 'L', 'Q', 'x', 'G', 'W', 'u'], ['B', 'B', 'e', 6701, 1889, 7173, 'P', 'R', 'i', '545', 'l', 'q', 'P', 'f', 'F', '6923', '9257', '9417', 'r', 't', 1799, 4639]