using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

         var initial = new List<int> { 2, 5, 6, -1, -3, -4 };

         initial.OrderBy(x => Math.Abs(x));

        foreach(var e in initial){

        Console.WriteLine(e);   

        }

        dummy();

    }

    public static void dummy(){

        var initial = new List<int> { 2, 5, 6,-1, -3, -4 };

            var dummyList = initial.FindAll(x => x < 0);

​

            initial .RemoveAll(x => dummyList.Contains(x));

​

            foreach (var e in dummyList)

            {

                initial .Add(e * -1);

            }

​

            initial.Sort();

​

            foreach (var e in dummyList)

            {

                var index = initial.FindIndex(x=>x==(e*-1));

                initial.RemoveAt(index);

                initial.Insert(index, e);

            }

        Console.WriteLine("\nthis is my solution");

        foreach(var e in initial){

            Console.WriteLine(e);

        }

    }

}