using System;
public class Program
{
public static void Main()
}
public class Shape
public double height;
public double width;
public virtual double CalculateSurface()
return 0;
public Shape (double width, double height)
this.width = width;
this.height = height;
public class Triangle : Shape
public Triangle (double width, double height)
: base(width, height)
public override double CalculateSurface()
return (height*width/2);