1------------------------------------------------------------------------------------------
2------------------------------------------------------------------------------------------
3------------------------------------------------------------------------------------------
4----2---------------------------------2-------------------------------------------------
5-----------------------3----4---5------------------------------------------------------
6---------2----3-----4----------------------------------------------------------------------


1-----------------------------------------------------------------------------------------------------------
2------------------------------------------------------------------------------------------------------------
3-----------------------------------------3-----------------------------------------------------------------
4----x--2--x--2--x--2---3--2--x--2--x-2------2----x---2---x---2---x--2-3-2---2------------------------------
5--------------------------------------------------------------------------------------------3----4-----5--
6-----------------------------------------------------------------------------------2--3--4----------------