Hint
In the first case, both sequence {1, 2} and {2, 1} are legal.In the second case, sequence {1, 2, 3}, {1, 3, 2}, {2, 1, 3}, {2, 3, 1}, {3, 1, 2}, {3, 2, 1} are legal, so the answer is 6 mod 5 = 1
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zhxs contest （hdu 5187 快速幂+快速乘法）
