#include <iostream>
#include <string>
#include <algorithm>
#include <utility>
#include <cmath>
#include <cstdlib>
#include <map>
#include <set>
#include <queue>
#include <vector>
using namespace std;

int main() {
	long long K; cin >> K;
	cout << 4 * K * K + 2;
}