In this task, you are given two lists A,B. Find the longest common subsequence in the lists A and B.
[6419, 3157, 'T', 8213, 'L', '1057', 'c', '7961', 'Q', 'Y', 1839], [9743, 7621, 'Y', 2825, 'L', '1057', 'c', '7961', 'w', 'M']