.
                                     G
                               l     lo     l
                             o      ba      o
                            b        l          b
                           a       P  u        a
                           l        s    s         l
                           P        y  S         P
                            u        S y        u
                              s        S         s
                                s       t       s
                                   y   e    y
                                        m