using System;

namespace chapter3
{
	/// <summary>
	/// Figure 的摘要說明。
	/// </summary>
	abstract public class Figure
	{
		protected double x=0,y=0;
		public Figure(double a, double b)
		{
			x=a;y=b;
		}
		public abstract void Area();
	}
	class Square : Figure
	{
		public Square(double a,double b): base(a,b){}
		public override void Area()
		{
			Console.WriteLine("The area of squre is {0}",x*y);
		}

	}
	class Circle :Figure
	{
		public Circle(double a):base (a,a){}
		public override void Area()
		{
			Console.WriteLine("The area of circle is {0}",x*x*Math.PI);
		}
	}
}