using System;

​

abstract class AbstractClass { 

    // Non abstract method 

    public int AddTwoNumbers(int Num1, int Num2) 

    { 

        return Num1 + Num2; 

    } 

    // An abstract method which  

    // overridden in the derived class 

    public abstract int MultiplyTwoNumbers(int Num1, int Num2); 

} 

// Child Class of AbstractClass 

class Derived : AbstractClass { 

    // implementing the abstract  

    // method 'MultiplyTwoNumbers' 

    // using override keyword, 

    public override int MultiplyTwoNumbers(int Num1, int Num2) 

    { 

        return Num1 * Num2; 

    } 

} 

// Driver Class 

public class geek { 

    // Main Method 

    public static void Main() 

    { 

        // Instance of the derived class 

        Derived d = new Derived(); 

        Console.WriteLine("Addition : {0}\nMultiplication :{1}", 

                                          d.AddTwoNumbers(4, 6), 

                                    d.MultiplyTwoNumbers(6, 4)); 

    } 

}