#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define ALL(v) v.begin(),v.end()
typedef long long ll;

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

int main(){
  ll k;
  cin>>k;
  
  if(k%2==0) cout<<4*k*k+2<<endl;
  else cout<<4*k*k+2*k-k/2*4<<endl;

  return 0;
}