using System;

using System.Text.RegularExpressions;

public class Program

{

    private static Regex FilePattern = new Regex(@"\/((bygg\d+)\/DokBrukerFiler\/file.*?\/)([^\/]+)", RegexOptions.Compiled);

    public static void Main()

    {

        var text = "/bygg1/DokBrukerFiler/filefoo/fdlkajsdf.abc /bygg1/DokBrukerFiler/filefoo/fdlkajsdf.def";

        foreach(Match match in FilePattern.Matches(text)) {

            Console.WriteLine(match.Groups[3].Value);

        }

    }

}