#include <bits/stdc++.h>

using namespace std;

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

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