C++比赛真题——猪队友_#include
C++比赛真题——猪队友_ios_02

//Author:PanDaoxi
#include <iostream>
using namespace std;
int main(){
	int n;
	long long a[10001]={0,0,1};
	cin>>n;
	for(int i=3;i<=n;i++) a[i]=(a[i-1]+a[i-2])*(i-1);
	cout<<a[n]<<endl;
	return 0;
}