#5677. CSES1717 圣诞派对
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CSES1717 圣诞派对
Christmas Party
There are n children at a Christmas party, and each of them has brought a gift. The idea is that everybody will get a gift brought by someone else. In how many ways can the gifts be distributed?
Input
The only input line has an integer n: the number of children.
Output
Print the number of ways modulo 10^9+7.
Constraints
Example
Input
4
Output
9