/*
TASK:minitime
LANG:C++
*/
#include <iostream.h>
#include <stdlib.h>

int main()
{int n;
cin>>n;
int a=n;
int p=n/2;
if(p*2!=n){
int x=p+1;
if(2+x>a)cout<<a;
else cout<<2+x;}
else {if(2+p>a)cout<<a;
else cout<<2+p;}

      system("PAUSE");
      return 0;
}
