In this task, you are given two lists A,B. Find the longest common subsequence in the lists A and B.
[6881, 'r', 9935, 6705, '7861', '5635', 'Q', '3881', 'm', '7311', 'a', '4321', 'S', 3411], ['U', 4649, 'l', 'U', 'N', '7861', '5635', 'Q', '3881', 'm', '7311', 'a', '4321', 'q', 7707, 'S', 3735, 'A', 3969, 1109]