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

int main() {
	int a;
	cin >> a  ;
	if (a == 1) {
		cout << "11";
	} else if (a != 1) {
		cout << (a - 1) * 4 + 1 + (4 * a + 5);
	}
	return 0;
}