#include <iostream>

int main ()
{
	float sum = 0;
	for(;;)
	{
		float number = 0;
		std::cout << "Enter a number: ";
		std::cin >> number;
		
		///// Variante 1
		///// if ( std::cin.good() )
		//
		///// Variante 2
		// bool is_okay = std::cin;
		// if ( is_okay )
		//
		///// Variante 3 
		if ( std::cin )
		{
			std::cout << "Thanks!  You entered: " << number << std::endl;
			sum += number;
			std::cout << "Current sum is: " << sum << std::endl;
		}
		else
		{
			std::cout << "\nOkay, this is it!" << std::endl;
			break;
		}

	}
	return 0;
}