In this task, you are given two lists A,B. Find the longest common subsequence in the lists A and B.
[3515, 2869, 'x', 'C', 'f', 'R', 'I', '4601', '725', '1733', 'a', 'U', 'w', 'w', '9547', '813', '6517', 'i', 'W', 'x', 'w', 8987, 'w', 'E', 1353, 'o', 'R', 'X', 'B', 641, 's', 1039, 2617, 'w'], [6879, 2561, 'd', 'j', 'x', 'C', 'f', 'R', 'I', '4601', '725', '1733', 'a', 'U', 'w', 'w', '9547', '813', '6517', 'i', 'W', 'x', 'V', 429, 251, 9833, 'M', 3223, 8197, 'n', 5719, 4283, 'k']