.


                     D                           D
              i     i  p     i             i    i  p     i
            p      D  i      p        p     D  i       p
          D          p         D    D         p           D
         i            D           i    i          D             i
        P         i      p        p p       i      p          p
         D        D    i         DD        D    i           D
           i           p          i     i           p            i
             p        D       p         p       D         p
               D      i     D               D    i     D
                        P                            p