#include <bits/stdc++.h>

using namespace std;

long sumOfGroup(long k) {
    if (k==0)
        return 0;
    long a = (k*(k-1))+1;
    long sum=0;
    for(long i=1;i<=k;i++)
    {
        sum+=a;
        a+=2;
    }
    return sum;
    // Return the sum of the elements of the k'th group.
}

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