using System;

    namespace test{         

        public class Program : Pstr

        {

            public static void Main()

            {

                Program o = new Program();

                Console.WriteLine(o.dod());

                Console.WriteLine(o.dod1());

            }

        }

        public abstract class Pstr : Iprs

        {

             public int i;

             public string dod()

             {

                return "dod()";

             }

             public string dod1()

             {

                return "dod1()";

             }

        }

        interface Iprs{

            string dod();

            string dod1();

        }

    }