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

/**************************************************************
	Problem: 1518
	User: wtq001
	Language: C++
	Result: Wrong Answer
****************************************************************/