#include <bits/stdc++.h>

using namespace std;

long sumOfGroup(int k) {
    // Return the sum of the elements of the k'th group.
    long result = 0;
    long start = 1;
    for(long i = 0; i < k; ++i)
        for(long j = 0; j < i; ++j)
            start += 2;
    for(long i = 0; i < k; ++i)
    {
        result += start;
        start += 2;
    }
    return result;
}

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