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