Tree Walker:
B
B.1
B.1.1
C
C.1
C.1.1
C.1.1.1
C.1.1.2
C.1.1.3
C.1.2
C.2.1
D
Tree Walker:
B
B.1
B.1.1
C
C.1
C.1.1
C.1.1.1
C.1.1.2
C.1.1.3
C.1.2
C.2.1
D