In this task, you are given two lists A,B. Find the longest common subsequence in the lists A and B.
[9881, 7753, 'i', 'j', '2949', '9461', '3633', '789', 'U', 7815], ['x', 'z', 'j', '2949', '9461', '3633', '789', 'l', 8475]