using System;

public class Program //Remove the "static" word here

{

    public void Main()

    {

        Console.WriteLine(ShowName("John"));

        Console.WriteLine(ShowName("John", "Smith"));

    }

    public string ShowName(string firstName)

    {

        return firstName;

    }

    public string ShowName(string firstName, string lastName)

    {

        return string.Format("{0} {1}", firstName, lastName);

    }

}