public static void Main(String[] args)
{
String phrase = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
String phrase1 = "HELLO WORLD";
String answer = Letters.HasUnique(phrase).ToString();
String directory = @"C:/Users/Public/chapter_01_practice.txt";
System.IO.File.WriteAllText(directory, answer);
}