/*

	Multi-line comments 


	Goal: The program will calculate the area of a circle.

*/


#include <iostream>	// cin, cout, fixed, showpoint, endl
#include <iomanip> 	// for setprecision

using namespace std;

int main()
{
	// 1. variable declaration
	const float PI = 3.14;
	cout << fixed << showpoint << setprecision(1);

	float radius, area;

	// 2. input
	cout << "Input the radius (-1 to quit) : ";
	cin >> radius;

	while( radius > 0 )	// quit the loop for negative radius
	{
		// 3. computing
		area = PI * radius * radius;

		// 4. output
		cout << "The area is: " << area << endl;  
		
		cout << "Input the radius (-1 to quit) : ";
		cin >> radius;
	}

	return 0;
}