Street Skater

       .
  ,    "--!"
    :
[], [], [], [], [], [], [R1], [L1].
 :
[], [], [R1], [R2], [], [], [L1], [L2].
   :
[], [], [], [], [], [], [R1], [R2].
   :
[], [], [], [], [R2], [L1], [L2], [R1].
   :
[], [], [], [], [] x2, [] 2.
   :
        .

 