#include <iostream>
#include <vector>
#include <set>
#include <queue>
#include <string>
#include <string.h>
#include <algorithm>
#include <stack>
#include <iomanip>
#include <ctime>
#include <map>
#include <cstdio>
#include <cmath>

using namespace std;

typedef long long ll;
typedef long double ld;

const int N = 100005;
const int inf = 1e9;

ll n, m, i, j, k, q, s, w, ans;


int main()
{

	cin >> k;

	n = k*(k + 1) / 2;
	m = n - k;

	cout << n*n - m*m << endl;

	return 0;
}