using System;

​

namespace Oooo

{

    class Base

    {

        public int Some { get; private set; }

​

        public Base()

        {

            Some = 12345;

        }

    }

​

    class Der : Base { }

​

    public class Program

    {

        public static void Main()

        {

            Der d = new Der();

            var pi = d.GetType().GetProperty("Some");

            pi.SetValue(d, 12);

            Console.WriteLine(d.Some);

        }

​

    }

}