using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace DesignModel
{
    public interface Factory
    {
        JS createjs();
    }
    public class JS
    {
        public int NumA { get; set; }
        public int NumB { get; set; }
        public virtual int GetResult()
        {
            return 0;
        }
    }
    public class Add1 : JS
    {
        public override int GetResult()
        {
            return NumA + NumB;
        }
    }
    public class Sub1 : JS
    {
        public override int GetResult()
        {
            return NumA - NumB;
        }
    }
    public class AddFactory : Factory
    {
        public JS createjs()
        {
            return new Add1();
        }
    }
    public class SubFactory: Factory
    {
        public JS createjs()
        {
            return new Sub1();
        }
    }
}

  Factory factory = new AddFactory();
            JS  js = factory.createjs();
            js.NumA = 1;
            js.NumB = 2;
            Console.WriteLine( js.GetResult());
            Factory f = new SubFactory();
            JS J= f.createjs();
            J.NumA = 9;
            J.NumB = 0;
            Console.WriteLine(J.GetResult());
            Console.ReadLine();