In this task, you are given two lists A,B. Find the longest common subsequence in the lists A and B.
['i', 5811, 'j', 3875, '9667', 'R', '2545', 'i', '8937', '6873', 'Q', 4657, 'e'], [2249, 'P', 'w', 9665, 6823, 'k', '9667', 'R', '2545', 'i', '8937', '6873', 't', 'W', 7533, 's', 'A', 3879]