using System;

using System.IO;

public class Program

{

    public static void Main()

    {

        /* https://docs.microsoft.com/de-de/dotnet/api/system.io.file.open?view=net-5.0 */

        foreach (var x in Path.GetInvalidFileNameChars())

        {

            Console.WriteLine("{0:c}", x);

        }

    }

}