using System;

public abstract class Shape{

    public int numSides;

    public Shape(int numSides){

        this.numSides = numSides;

    }   

    private int NumSides{

        get { return numSides;}

    }

​

    public abstract double getArea();

    public abstract double getPerimeter();

}

​

public class Rectangle: Shape{

    private double width;

    private double height;

    public Rectangle(double width, double height):base(4){

        this.width = width;

        this.height = height;

    }

    public override double getArea(){

        return width*height;

    }

    public override double getPerimeter(){

        return 2*width+2*height;

    }

}

​

public class IsoscelesTriangle: Shape{

    private double Base;

    private double height;

    public IsoscelesTriangle(double Base, double height):base(3){

        this.Base = Base;

        this.height = height;

    }

    public override double getArea(){

        return Base*height/2;

    }

    public override double getPerimeter(){

        return Base+ 2*Math.Sqrt((Base/2)*(Base/2)+height*height);

    }

}

​

​

public class Program

{

    public static void Main()

    {

​

    }

}