.
                                  O
                          b­     b  s       b
                       s         e  s          s
                    e            s  i              e
                   s             v  e               s
                  s                C                   s
                 i                  o                    i
                v                  m                    v
               e                   p                      e
               C                   u                      C
               o                 l     s                   o
              m               i        v                m
               p               e        D                p
               u                i       s              .  u
                 l                 o   r                 l
                   s                 d                 s
                      i               e               i
                         v           r           v
                              e      O      e
                 ­                     b
                                      s
  ­                                    e
                           ­           s
                                      s