#include<bits/stdc++.h>
using namespace std;
int main(){
	int a;
	cin>>a;
	if(a%2==1) cout<<a/2+1;
	else cout<<a/2+a/2+1;
}
/**************************************************************
	Problem: 1558
	User: panyuchen
	Language: C++
	Result: Accepted
	Time:36 ms
	Memory:2072 kb
****************************************************************/