using System;

​

namespace Cities_and_Villages

{

    abstract class Toponym

    {

        public abstract string Name { get; }

        public DateTime FoundationDate { get; set; }

        public static int GetAge(DateTime foundationDate)

        {

            return foundationDate.Year - DateTime.Now.Year;

        }

        public int Population

        {

            private set { if (value >= 0) Population = value; }

            get { return Population; }

        }

    }

​

    class City : Toponym

    {

        private string name;

        City(string name /*, DateTime foundationDate, int population*/)

        {

            Rename(name);

            /*FoundationDate = foundationDate;

            Population = population;*/

        }

    public override string Name

    {

        get

            {

            return @"City " + name;

            }

    }

        public void Rename(string name)

        {

            if (string.IsNullOrEmpty(name))

                throw new ArgumentException("name is empty");

            this.name = name;

        }

    }

        public class Programm

        {

            public static void Main(string[] args)

            {

                //City a = new City();

            }

        }

}

​

​