using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        List<int> lstInput = new List<int>(){1,2,3,4,5,6,7,9,10,11,22};

        List<List<int>> lstSubLists = new List<List<int>>();

          int firstKey = lstInput[0];

                    int lastKey = 0; 

                    bool resetFirst = false;

                    List<int> lstTemp = new List<int>();

                    for(int i=1;i<=lstInput.Count;i++)

                    {

                        if(resetFirst)

                        {

                            firstKey = lstInput[i-1];

                            resetFirst= false;

                            //Console.WriteLine("Reset At i = "+ i + " First Key  = " + firstKey);  

                        }

                        if (i<lstInput.Count && lstInput[i-1] == (lstInput[i]-1))

                        {

                            lstTemp.Add(lstInput[i-1]);

                            resetFirst = false;

                        }

                        else

                        {

                             lastKey = lstInput[i-1];

                             lstTemp.Add(lastKey);

                            lstSubLists.Add(lstTemp);

                            lstTemp = new List<int>();

                             Console.WriteLine("i = "+ i + " First Key  = " + firstKey + " LastKey = " + lastKey);

                             resetFirst = true;

​

                        }

                    }

                   Console.WriteLine("\n\nSub Lists \n\n");

                  foreach(List<int> lstOfInt in lstSubLists)

                  {

                     Console.WriteLine( string.Join(",",lstOfInt.ToArray())+"\n" );

                  }

    }

}