INTRO: first part. --+-------------------------+- X2 --+---1-1--6-4--------------+- --+---2-2--7-5--1-1-1-------+- --+---2-2--7-5--2-2-2--3----+- --+--------5-3--2-2-2--3----+- --+--------------------1----+- INTRO: second part. --+---0-0-5----------------------------+- --+---------5-6-6-6-3--0-0-5-----------+- --+--------------------------5-4-4-4-2-+- --+------------------------------------+- --+------------------------------------+- --+------------------------------------+-