#include<bits/stdc++.h>
using namespace std;
int main(){
	int x,h;
	cin>>x;
	if(x%2==1){
		h=x/2+1;
	}else{
		h=x+1;
	}
	cout<<h;
	return 0;
}

/**************************************************************
	Problem: 1558
	User: tangkaixuan
	Language: C++
	Result: Accepted
	Time:42 ms
	Memory:2072 kb
****************************************************************/