using System;

delegate int arithmetic ( int x , int y);

​

public class maths

{

    public static int add(int a , int b)

    {

        return (a+b);

    }

    public static int sub(int a , int b)

    {

        return (a-b);

    }

}

​

​

​

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

        arithmetic op1 = new arithmetic(maths.add);

        arithmetic op2 = new arithmetic(maths.sub);

        int res1 = op1(10,20);

        int res2 = op2(30,10);

        Console.WriteLine("sum = {0}",res1);

        Console.WriteLine("sub = {0}",res2);

    }

}