In this task, you are given two lists A,B. Find the longest common subsequence in the lists A and B.
[8657, 7293, 'Y', 'e', 'T', 'w', 'm', '7315', '3373', 'l', 'H', 'i'], [3903, 2107, 'l', 'S', 'e', 'T', 'w', 'm', '7315', '3373', 'l', 2105, 8017, 'S', 3557, 'm', 3257, 'R']