.
                                   Sh
                          h       re        h
                      r            w             r
                   e               S                 e
                  w               h                  w
                  S              r    e                S
                  h              w  S                h
                   r              h  r                r
                     e              w               e
                       w            S            w
                          S          h         S
                              h      ~      h