#include <bits/stdc++.h>

using namespace std;

long long sumOfGroup(long long k)
{
    long long sum = 0;
    for (long long i = 0; i < k; ++i)
    {
        sum += k * (k - 1) + 1 + i * 2;
    }
    return sum;
}

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