| | |--> 1.c
  | | `--> 1.e
  | | | +--> 1.D
  | | | +--> 3.AB
  | | | +--> 3.E
  | | | +--> 4.C
  | |   ---> 3.C
  | |   +--> 4.ACD
  | | +--> 2.c
  | | `--> 2.d