#include <bits/stdc++.h>
using namespace std;
int main()
{
int n,s=1,a=0;
cin>>n;
for(int i=1;i<=n;i++){
	s=1;
	for(int j=1;j<=i;j++){
		s*=j;
	}
	if(i%2==0){
			a-=s;
		}else a+=s;
}
cout<<a;
return 0;

}

/**************************************************************
	Problem: 1518
	User: mc002
	Language: C++
	Result: Accepted
	Time:18 ms
	Memory:2072 kb
****************************************************************/