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

int main()
{
	int humanYears;
	
	cout << "Enter your age and I will calculate how old you are in dog years!\n";
	cin >> humanYears;

	if (!cin) {
		cerr << "Please enter an actual age.\n";
		return EXIT_FAILURE;
	}
	if (humanYears < 0) {
		cerr << "You must be older than 0 for me to calculate your dog age!\n";
		return EXIT_FAILURE;
	}

	cout << "You are " << humanYears * 7 << " years old in dog years!\n";
	return EXIT_SUCCESS;
}