In this task, you are given two lists A,B. Find the longest common subsequence in the lists A and B.
[5031, 'Y', 'G', 'L', 6477, 7521, '9249', 'K', '9613', 't', 'h', 'I', 'b', '2137', '9975', '153', 'K', 'U', '4835', 'r', 'C', '6535', 'c', 't', 1119, 649, 3615, 6273, 'W', 1639, 2587], ['r', 2363, '9249', 'K', '9613', 't', 'h', 'I', 'b', '2137', '9975', '153', 'K', 'U', '4835', 'r', 'C', '6535', 'c', 'x', 3887]