.
                                 ex
                           x    s t     x
                          s     e n      s
                          t      d e       t
                         e        d         e
                         d     w   a      d
                         w    r     r      w
                          a     a   n      a
                           r     t   y      r
                             r      e      r
                               a   X    a
                                    n
                                    t
                                    y