UVa 913 - Joana and the Odd Numbers

// UVa 913 - Joana and the Odd Numbers

#include <iostream>
using namespace std;

#define datatype unsigned long long int

int main() {
	datatype n;
	while (cin >> n) {
		datatype m = (n + 1) / 2;
		cout << 3 * (2 * m * m - 3) << endl;
	}
	return 0;
}