//This program calculates the area of a circle.
//The formula for the area of a circle is Pi times
//the radius squared. Pi is 3.14159.
#include <iostream>
#include <cmath> //needed for pow function
using namespace std;

int main()
{
	const double PI=3.14159;
	double area, radius;
	
	cout<<"This program calculates the area of a circle.\n";
	cout<<"What is the radius of the circle? ";
	cin>>radius;
	area=PI*pow(radius,2.0);
	cout<<"The area is "<<area<<endl;
	return 0;
}