#include <bits/stdc++.h>

using namespace std;

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

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