#include <bits/stdc++.h>

using namespace std;

using Integer = long long;

Integer sumOfGroup(int k) 
{
    auto const K = Integer{k} * (k - 1) / 2;
    
    auto const x_min = 2 * K + 1;
    auto const x_max = x_min + 2 * (k - 1);
    
    if(k % 2 == 0)
    {
        return  (x_max + x_min) * (k / 2);
    }
    else
    {
        return (x_max + x_min) / 2 * k;
    }
}

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