using System;

using System.Linq;

using System.Xml;                   

using System.Xml.Linq;

using System.Collections; 

using System.Collections.Generic;

using System.Data;

using System.Data.DataSetExtensions;

using System.Data.Linq;

using System.Text;

using System.Text.RegularExpressions;

public class Program

{

    public static void Main()

    {

        List<String> preferences = new List<String> { "first","second","third" };

        List<string> mylist = new List<string>() {"four", "second", "first","third" };

        IEnumerable<string> orderedData = mylist.OrderBy(item => 

                                         {

                                              var index = preferences.IndexOf(item);   

                                              return index>=0 ? index: int.MaxValue;

                                         });

        orderedData.Dump();

    }

}