Find the number of surjective mappings f:{1,2,3,4,5,6}→{A,B}f: \{1, 2, 3, 4, 5, 6\} \to \{A, B\}f:{1,2,3,4,5,6}→{A,B} such that f−1(A)f^{-1}(A)f−1(A) has more elements than f−1(B)f^{-1}(B)f−1(B).
20
22
31
32