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

int main() {

	double miles {0};

	cout << "This program will calculate how much it will cost to go X miles with a taxi. Type the amount of miles you would like to go.\n"; 
	cin >> miles;

	if (!cin || miles <= 0) {
		cerr << "Try again.\n";
		return EXIT_FAILURE;
	}

	double dollars {miles * 3.5 + 3};
	cout << "It will cost you $" << dollars << "\n";

	return EXIT_SUCCESS;
}