using System;

public class Test
{
	static void Speak(dynamic animal)
	{
  	   animal.Talk();
	}
	public static void Main()
	{
		dynamic obj1 = new Duck();
		obj1.Walk();
		Speak(obj1);
		dynamic obj2  =new Person();
		obj2.Walk();
		Speak(obj2);
	}
}

public class Duck 
{
	public void Walk()
	{
		Console.WriteLine("Duck walking on the street");
	}

	public void Talk()
	{
        Console.WriteLine("quack quack quack");
	}
}
public class Person
{
	public void Walk()
	{
		Console.WriteLine("Person walking on the street");
	}

	public void Talk()
	{
      Console.WriteLine("Hello World!");
	}
}