#include <bits/stdc++.h>

using namespace std;

long sumOfGroup(int k) {
    long n,i,x=0,b=0,a[1000000],c;
    c=k;
    n=c*(c+1);
    for(int i=1;i<=n;i++)
    {
        if(i%2!=0)
        {
                a[x]=i;
                x++;
            }
       }
    for(i=x-1;i>=x-k;i--)
    {
        b=b+a[i];
     }
    
    return b;
}

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