.
                                 P
                     u       u   s       u
                  s           s   y            s
                s               p                 s
               y                u                  y
              p                 s                    p
              u             s       y               u
              s            p          u              s
               s             s        s               s
                y                y                  y
                  p              p                p
                    u            u             u
                       s          s           s
                           s       s      s
                                   y