#include <bits/stdc++.h>

using namespace std;

unsigned long long sumOfGroup(long k) {
    // Return the sum of the elements of the k'th group.
    unsigned long long start = 1ULL+k*(k-1);
    return (k*(start+k-1ULL));
}

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