#include <bits/stdc++.h>

using namespace std;

long long int sumOfGroup(long long int k) {
    long long int start=k*k-k+1;
    //long long int end=start+(k-1)*2;
    long long int sum=(k*(2*start+(k-1)*2))/2;
    return sum;
    // Return the sum of the elements of the k'th group.
}

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