using System;

namespace ConsoleApp1
{

    abstract class Figure
    {
        protected int posX,posY;

        abstract public double Square();

    }

    class Triangle : Figure
    {
        int h, m;
        public Triangle(int h, int m)
        {
            this.h = h;
            this.m = m;

        }
        override public double Square()
        {
            return (h * m)/2;
        }
    }

    class Circle:Figure
    {
        int r;
        public Circle(int r)
        {
            this.r = r;
        }
        public override double Square()
        {
            return (Math.PI * r * r);
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            int r = 1;
            Figure circles = new Circle(r);
            Figure triangles = new Triangle(5, 10);
            Console.WriteLine("Площадь круга равна: " + circles.Square());
            Console.WriteLine("Площадь треугольника равна: " + triangles.Square());
        }
    }
}