using System;

using System.Globalization;

public class Program

{

    public static void Main()

    {

        string format = "yyyyMMddHHmmssfff";

        string dateTime = "20191211034422455";

        var x = DateTime.ParseExact(dateTime, format, CultureInfo.InvariantCulture);

        var result = x.ToString("dd-MM-yyyy HH:MM");

        Console.WriteLine(result);

    }

}