#include <iostream>
#include <bits/stdc++.h>
using namespace std;

#define pb push_back
#define ll long long
#define F first
#define S second
typedef pair<int,int>ii;
typedef pair<vector<int>,int>vii;
const int N=100005;


int main()
{
   // freopen("test.in","r",stdin);
    //freopen("kth.out","w",stdout);
    ll k;
    cin>>k;
    ll sum = k*(k+1)/2ll;
    ll total=sum*sum - (sum-k)*(sum-k);
    cout<<total;
    return 0;
}