#include <bits/stdc++.h>
using namespace std;
int main (){
  int a,b,s=1;
  cin>>a;
  for(b=1;b<a;b++) s=s+s*b;
  
  cout<<s;

}

/**************************************************************
	Problem: 1004
	User: wtq001
	Language: C++
	Result: Accepted
	Time:7 ms
	Memory:2072 kb
****************************************************************/