using System;

using System.Collections.Generic;

using System.Text;

​

public class Program

{

​

    public static string Solution(string A, string B) {

        return "";

    }

    public static void Main()       

    {   

        Console.WriteLine("Solution Output: {0} ", Solution("boom", "gloom")); // "oom"

​

        Console.WriteLine("Solution Output: {0}", Solution("brake", "grape")); // "e"

​

        Console.WriteLine("Solution Output: {0}", Solution("first", "second")); // ""

    }

}