In this task, you are given two lists A,B. Find the longest common subsequence in the lists A and B.
['C', 9451, 'a', 'c', '1879', '7201', 'H', '3431', 'u', 17], ['t', 37, '1879', '7201', 'H', '3431', 'X', 7267, 'Z']