#include<bits/stdc++.h>
#define int long long
using namespace std;

signed main(){
  int k; cin >> k;
  int p = 1 + 2*k;
  int q = (p-2)/2 * (p-2);
  int r = ((p-2)/2+1)*p;
  cout << q + r + p/2 + p/2+1 << endl;
}