#include <bits/stdc++.h>

using namespace std;

long sumOfGroup(int k) {
    k--;
    long index = (long)k * (2 + k - 1) / 2 + 1;
    k++;
    long first = index * 2 - 1;
    long sum = ((long)k) * (2 * first + (k - 1) * 2) / 2;
    return sum;
}
int main() {
    int k;
    cin >> k;
    long answer = sumOfGroup(k);
    cout << answer << endl;
    return 0;
}