#include <bits/stdc++.h>

using namespace std;

long sumOfGroup(int k) {
    long i;
    long a = pow(k,2) - k + 1;
    long b = pow(k,2) - k + 1;
    long x = k-1;
    i = 2;
    while(x--) {
        a = a + b + i;
        i = i + 2;
    }
    return a;
}

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