l-------------------------------------5---8------------------------------------
l-----------------------------5--8---------------------------------------------
l-----------------------5--7---------------------------------------------------
l----------------5--7----------------------------------------------------------
l----------5--8----------------------------------------------------------------
l----5--8----------------------------------------------------------------------

then do it back wards
l----5--8----------------------------------------------------------------------
l----------5---8---------------------------------------------------------------
l-----------------5--7---------------------------------------------------------
l------------------------5--7--------------------------------------------------
l------------------------------5---8-------------------------------------------
l----------------------------------------5--8----------------------------------