#include <bits/stdc++.h>

using namespace std;

unsigned long sumOfGroup(unsigned long k) {
    unsigned long size_of_group = k;

    //get first odd num of group
    unsigned long n = 0;
    for(unsigned long i = k - 1; i >= 1; --i) {
        n += i;
    }

    n = (2 * n) + 1;

    unsigned long sum = 0;
    for(unsigned long i = 0; i < k; ++i) {
        sum += n;
        n += 2;
    }

    return sum;
}

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