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

/*
Introducing cin and cerr, two more members of namespace std.
And another possible exit status number, EXIT_FAILURE.

The if (!cin) means "if cin is in an unhealthy state as a result
of the failure of the previous attempt at input".
*/

int main()
{
	cout << "Please type the price and press RETURN.\n";   //or press ENTER
	int price {0};   //This variable will die whenever we return from main.
	cin >> price;

	if (!cin) {
		cerr << "Sorry, that wasn't an acceptable number.\n";
		return EXIT_FAILURE;
	}
						  
	cout << "Thank you, the variable contains " << price << ".\n";
	return EXIT_SUCCESS;
}