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

typedef long long ll;
#define int ll
#define _FastIO ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define pii pair<int , int>
#define pb emlpace_back
#define F first
#define S second
const int mod = 998244353;
const int MAXX = 1e6 + 5;

int n;
int a[MAXX];

signed main()
{
    _FastIO;
    cin >> n;
    cout << (4 * n * n) + 2 << endl;
    return 0;
}