// C# Program to Perform all Basic Arithmetic Operations using interface
using System;
interface myinterface
{
    void addition(int a,int b);
    void multiplication(int a, int b);
    void division(int a, int b);
    void substraction(int a, int b);
}
class a : myinterface
{
    public void addition(int a,int b)
    {
        int result;
        result = a + b;
        Console.WriteLine("addition is : {0}",result);
       
    }
    public void multiplication(int a, int b)
    {
        int result;
        result = a * b;
        Console.WriteLine("multiplication is : {0}",result);
       
    }
    public void division(int a, int b)
    {
        int result;
        result = a / b;
        Console.WriteLine("division is : {0}",result);
       
    }
    public void substraction(int a, int b)
    {
        int result;
        result = a - b;
        Console.WriteLine("substraction is : {0}",result);
       
    }
}
class program
{
        public static void Main()
        {
            int a,b;
            String option;
            Console.WriteLine("enter value");
            a=Convert.ToInt32(Console.ReadLine());
            Console.WriteLine("enter value");
            b=Convert.ToInt32(Console.ReadLine());
            Console.WriteLine("1.Addition");
            Console.WriteLine("2.multiplicaition");
            Console.WriteLine("3.divition");
            Console.WriteLine("4.subtraction");
            option =(Console.ReadLine());
              a a1 = new a();
            switch(option)
            {
                case"1":
                  a1.addition(a,b);
                break;
                case "2":
                a1.multiplication(a, b);
                break;
                case "3":
                a1.division(a, b);
                break;
                case "4":
                a1.substraction(a, b);
                break;
                 default:
                Console.WriteLine("invalid option");
                break;
        }
        Console.Read();
    }
}