#include<bits/stdc++.h>
using namespace std ;
#define ll long long
int main()
{

    #ifdef jamil993
      freopen("Input.txt" , "rt" , stdin ) ;
    #endif // jamil993

    ll n ;
    cin >> n ;

    ll res = (n*(n+1))/2 ;
    ll tak = res*res ;

    ll hav = res - n ;

    ll tak2 = hav*hav ;

    cout << tak - tak2 << endl ;





}