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


int main()
{
    double celsius {0.0};
    cout << "Enter the temperature in Celsius (minimum -273.15):\n";
    cin >> celsius;

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

    if (celsius < -273.15) {
        cerr << "Sorry, the temperature cannot be below absolute zero (-273.15°C).\n";
        return EXIT_FAILURE;  
    }

   
    double fahrenheit {celsius * 9.0 / 5.0 + 32.0};

    cout << celsius << " degrees Celsius is equal to "
         << fahrenheit << " degrees Fahrenheit.\n";

    return EXIT_SUCCESS;  
}