------------------------------- ------------------------------- X4 -------------------8----------- --8---1-----3------------------ ------------------------------- ------------------------------- X1 ---------------------------3--8 --8--3---1--8---3---1---8------ ----------------------- ----------------------- X5 -----------------8----- --8---1----3----------- ----------------------------------- ----------------------------------- X2 -----3---5---1-------8-8-7-8-7-8--- --8--------------3-----------------