using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Area_calc_App
{
    class Program
    {
        
        class Area
        {
            protected float vertical_length;
            protected float horizontal_length;
            
            public Area (float vertical, float horizontal)
            {
                this.vertical_length = vertical;
                this.horizontal_length = horizontal;

            }
            public virtual float Calc_area()
            {
                return this.vertical_length * this.horizontal_length;
            }

            public virtual void areaShow()
            {

            }
        }

        class Square : Area
        {
            public Square(float vertical, float horizontal) : base(vertical, horizontal)
            {

            }

            public override float Calc_area()
            {
                return base.Calc_area();
            }
            public override void areaShow()
            {
                Console.WriteLine("四角形の面積(S={0})を表示します。", this.Calc_area());
            }
        }

        class Triangle : Area
        {
            public Triangle(float bottom, float height):base(bottom,height)
            {
 
            }

            public override float Calc_area()
            {
                return base.Calc_area() / 2.0F;
            }
            public override void areaShow()
            {
                Console.WriteLine("三角形の面積(S={0})を表示します。", this.Calc_area());
            }
        }

        class Trapezoid : Area
        {
            public Trapezoid(float Upperbottom, float Lowerheight, float height) : base(Upperbottom + Lowerheight, height)
            {

            }

            public override float Calc_area()
            {
                return base.Calc_area() / 2.0F;
            }
            public override void areaShow()
            {
                Console.WriteLine("台形の面積(S={0})を表示します。", this.Calc_area());
            }
        }
        static void Main(string[] args)
        {
            /*
            Area a1 = new Square(5.0F, 10.0F);
            a1.areaShow();
            Area a2 = new Triangle(5.0F, 10.0F);
            a2.areaShow();
            Area a3 = new Trapezoid(5.0F,5.0F,10.0F);
            a3.areaShow();
            */
            List<Area> a = new List<Area>();
            a.Add(new Square(5.0F, 10.0F));
            a.Add(new Triangle(5.0F, 10.0F));
            a.Add(new Trapezoid(5.0F, 5.0F, 10.0F));

            foreach (Area s in a)
            {
                s.areaShow();
            }

            return;
        }
    }
}