using System;

class HINH

    {

        public string Ten { get; set; }

        public string MauSac { get; set; }

        public virtual void NhapHinh(string ghiChu)

        {

            Console.WriteLine(ghiChu);

            Console.WriteLine("Nhap ten hinh:");

            this.Ten = Console.ReadLine();

            Console.WriteLine("Nhap mau sac:");

            this.MauSac = Console.ReadLine();

        }

        public virtual double TinhChuVi()

        {

            return 0;

        }

    }

​

class HINHTRON : HINH

    {

        public DIEM I { get; set; }

        public double R { get; set; }

        public override void NhapHinh(string ghiChu)

        {

            base.NhapHinh(ghiChu);

            this.I.Nhap("Nhap tam I: ");

            Console.WriteLine("Nhap ban kinh:");

            this.R = double.Parse(Console.ReadLine());

        }

        public override double TinhChuVi()

        {

            return 2 * this.R * Math.PI;

        }

​

    }