| | |--> 2. c
  | | |--> 2. d
  | | |--> 2. e
  | | |--> 3. d
  | | `--> 3. e
  | |   +--> 3.C
  | |   +--> 4.ACD
  | | |--> 2.r.
  | | |--> 3.r.