using System;

public class Parent
{
	public virtual String this[String input]
	{
		get
		{
			return input;
		}
	}
}

public class Child : Parent
{
	public override String this[String input]
	{
		get
		{
			return base [input];
		}
	}
}

public class Test
{
	public static void Main()
	{
	}
}