#include <bits/stdc++.h>

using namespace std;

#define ll long long int

ll get_sum(ll k){
    return k * (k + 1) - 1;
}

ll sumOfGroup(int k) {
    // Return the sum of the elements of the k'th group.
    ll upper = get_sum(k);
    ll c = k;
    ll result = 0;
    while(c-->0){
        result += upper;
        upper -= 2;
    }
    return result;
}

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