#include <bits/stdc++.h>

using namespace std;

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

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