#include <iostream>

long kth_odd(int k) 
{
    return 1l + 2 * (k - 1);
}

long sum_of_group(int k) 
{
    long first_of_group = kth_odd(k + 1);
    long last_of_group = kth_odd(2 * k);
    
    return k * (first_of_group + last_of_group) / 2;
}

int main() {
    using std::cin;
    using std::cout;
    using std::endl;
    
    int k;
    cin >> k;
    long answer = sum_of_group(k);
    cout << answer << endl;
    return 0;
}