In this task, you are given two lists A,B. Find the longest common subsequence in the lists A and B.
[4215, 'n', 'G', '5307', 'f', 'G', 'Y', 3509, 1981], [7189, 2991, 9595, '5307', 'f', 'G', 1723, 6907, 'f']