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

}
/**************************************************************
	Problem: 1518
	User: houshanglin
	Language: C++
	Result: Accepted
	Time:11 ms
	Memory:2072 kb
****************************************************************/