#include <bits/stdc++.h>

using namespace std;

long sumOfGroup(int k) {
    long first = 1l * (k - 1) * k + 1;
    return first * k + 1l * k * (k - 1);
}

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