#include <iostream>
#include <cstdlib>
using namespace std;

int main()
{
	cout << "Please type the hour (0–23): ";
	int hour {0};
	cin >> hour;

	if (!cin) {
		cerr << "Sorry, that wasn't a number.\n";
		return EXIT_FAILURE;
	}

	if (hour < 12) {                            // before noon
		cout << "Good morning\n";
	} else if (hour < 17) {                     // 12:00–16:59
		cout << "Good afternoon\n";
	} else if (hour < 21) {                     // 17:00–20:59
		cout << "Good evening\n";
	} else {                                    // 21:00–23:59
		cout << "Good night\n";
	}

	return EXIT_SUCCESS;
}