gistfile1.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            Subclass s = new Subclass();
            s.test();
            Console.ReadLine();
        }

        public interface IInterface
        {
            void test();
        }

        public abstract class baseclass
        {
            public void test()
            {
                Console.WriteLine("baseclass");
            }
        }
        
        public class Subclass:baseclass,IInterface
        {
            
        }
        
        
        
    }
}