ABCD
ABC
AB
A
B
AC
C
BC
ABD
AD
D
BD
ACD
CD
BCD
ABCE
ABE
AE
E
BE
ACE
CE
BCE
ABCFG
ABCF
ABF
AF
F
BF
ACF
CF
BCF
ABCG
ABG
AG
G
BG
ACG
CG
BCG
ABFG
AFG
FG
BFG
ACFG
CFG
BCFG