public static void Main(string[] args)
{
Console.Write("Enter a valid 10 digit ISBN Number ");
string isbn = checkIsbnClass.DestabilizeIsbn(Console.ReadLine()); // Normalizes the input and puts it on string "str"
Isbn isbn = new Isbn(Console.In)
if (!isbn.CheckLength())
{
Console.WriteLine("The number you have entered is not a valid ISBN try again."); // Print invalid number
}
}
