Total unique words formed from 2x2.txt => 64
a
ab
abc
abcd
abd
abdc
ac
acb
acbd
acd
acdb
ad
adb
adbc
adc
adcb
b
ba
bac
bacd
bad
badc
bc
bca
bcad
bcd
bcda
bd
bda
bdac
bdc
bdca
c
ca
cab
cabd
cad
cadb
cb
cba
cbad
cbd
cbda
cd
cda
cdab
cdb
cdba
d
da
dab
dabc
dac
dacb
db
dba
dbac
dbc
dbca
dc
dca
dcab
dcb
dcba