using System;

interface Interfaz {
	void Metodo();
}

struct S : Interfaz
{
	public void Metodo()
	{
		Console.WriteLine("OK");
	}
}

public class Test
{
	public static void Main()
	{
	    S s1 = new S();
	    Interfaz s2 = new S();
	    
	    Interfaz i1 = s2;
	
	    S s3 = (S)i1;   // Unboxing
	
	    Interfaz i2 = s3;      // Boxing
	
	    i1.Metodo();
	    s2.Metodo();
	}
}