#include <bits/stdc++.h>

using namespace std;

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

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