using System;


public class Point
{
	private double x, y;

	public Point(double x, double y)
	{
		this.x = x;
		this.y = y;
	}

	public double X
	{
		get { return x; }
		set { x = value; }
	}

	public double Y
	{
		get { return y; }
		set { y = value; }
	}
}


	/*
	Write a class Circle that has 
	2 fields: double radius; Point center;
	1 constructor with 3 parameters: double r, double center_x, double center_y;
	1 property that allows access to the radius
	1 one method to compute the area
	*/

class Circle
{
	private double radius;
	private Point center;
		
	public const double PAI = 3.1415926;

	public Circle(double r, double cx, double cy)
	{
		radius = r;
		center = new Point(cx, cy);			
	}

	public double Radius
	{
		get
		{
			return radius;
		}
		set
		{
			radius = value;
		}
	}
	public double Area()
	{
		double area = PAI * radius * radius;
		return area;
	}		
}

class CircleTest
{			
	public static void Main()
	{
		Circle the_circle = new Circle(2.0, 5.0, 6.5);
		Console.WriteLine("The circle area is {0}", the_circle.Area());
	}		
}