#include <iostream>
#include <algorithm>
using namespace std;

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(0);
	long long k; cin >> k;
	cout << (k * 2 + 1LL) * (k * 2 + 1LL) - (k * 4 - 1LL) << '\n';
	return 0;
}