using System;

using System.Collections.Generic;

​

public class Program

{

    public static void Main()

    {

        var prefix = @"\-";

        Console.WriteLine((DateTime.Parse("10/26/2019 22:44") - DateTime.Parse("10/25/2019 23:22")).ToString($@"{prefix}h\:mm"));

        Console.WriteLine((DateTime.Parse("10/25/2019 11:44") - DateTime.Parse("10/25/2019 23:22")).ToString(@"h\:mm"));

        Console.WriteLine((DateTime.Parse("10/26/2019 17:00") - DateTime.Parse("10/26/2019 08:00")).ToString(@"h\:mm"));

    }

}

​