#include <bits/stdc++.h>

using namespace std;
#define ll long long int

ll sumOfGroup(ll k) {
    // Return the sum of the elements of the k'th group.
    ll first = (ll)((k -1)*k+1);
    ll l = k - 1;
    ll product = (ll)(k*l);
    
    ll sum = (ll)(k * first + product);
    return sum;
}

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