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()

    {

        int[,] list = new int[2,2] {{1,2},{3,4}};

        list.Cast<int>() 

            .Select((x,i)=> new {x, index = i/list.GetLength(1)})

            .GroupBy(x=>x.index)

            .Select(x=>x.Select(s=>s.x).ToList()).Dump();

    }

}