Codeforces round 691(div.2)B.Move and Turn

#include<bits/stdc++.h>
using namespace std;
int main()
{
  int n;
  scanf("%d",&n);
  if(n%2==1&&n!=1)
  {
    int res=0;
    for(int i=1;i<=n;i+=2)
    {
      res+=8+4*(i/2-1);
    }
    printf("%d\n",res);
  }
  else if(n==1)
  {
    printf("4\n");
  }
  else
  {
    printf("%d\n",(n/2+1)*(n/2+1));
  }
}