#include <bits/stdc++.h>

using namespace std;

long sumOfGroup(int k) {
	long sum = 0, firstNumberOfGroup = 1;
	int partOfGroup = 1;

	while (partOfGroup != k) {
		firstNumberOfGroup += 2 * partOfGroup;
		partOfGroup++;
	}

	while (k != 0) {
		sum += firstNumberOfGroup;
		firstNumberOfGroup += 2;
		k--;
	}

	return sum;
}

int main() {
    int k;
    cin >> k;
    long answer = sumOfGroup(k);
    cout << answer << endl;
    return 0;
}