#include <bits/stdc++.h>

using namespace std;

long sumOfGroup(int k) {
    long temp = 0, number = 1;
    
    for (int count = 1; count <= k; count++){
        for (int tries = 1; tries <= count; tries++, number+=2){
            if (count != k){
                number += (count) * 2;
                break;
            }
                temp += number;
        }
    }
    return temp;
}

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