using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Runtime.InteropServices;
 
namespace test
{
    public interface IClassMath
 
    {
        int add(int a, int b);
        int sub (int a, int b);
    }
    [ClassInterface(ClassInterfaceType.None)]
 
    public class ClassMath : IClassMath
    {
        public int add(int a, int b)
        {
           return a+b;
        }
       public int sub(int a, int b)
        {
           return a-b;
        }
    }
  }