#include <iostream>
#include <cstdio>

using namespace std;

int main() {
	long long n, ans;

	cin >> n;

	if (n % 2 == 1) {
		ans = 1 + n;
	} else if (n == 2) {
		ans = 1;
	} else {
		ans = 1 + n / 2;
	}
	cout << ans << endl;
	return 0;
}