#include <bits/stdc++.h>

using namespace std;

unsigned long long sumOfGroup(unsigned long long k) 
{
    
   unsigned long long t,a,sum;
    t=(k*(k-1))/2;
    t=t+1;
    a=1+(t-1)*2;
    sum=k*(a+k-1);
  return sum;
}

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