a-a a-b a-c a-z aaa aab aac aao aar aay aaz ab- aba abb abc abo abr aby abz ac- aca acb acc aco acr acy acz aoa aob aoc aoo aor ar- ara arb arc aro arr ary arz ay- aya ayc ayo ayr ayz az- aza azb azo azy azz baa bab bac bao bar bay baz bba bbb bbc bbo bbr bby bca bcb bcc bco bcr bcy bcz boa bob boc boo bor boy boz bra brb bro brr bry brz by- bya byc byo byr byz bza bzo bzr bzz c-- caa cab cac cao car cay caz cba cbb cbc cbo cbr cby cbz cca ccb ccc cco ccr ccz co- coa cob coc coo cor coy coz cra crb crc cro crr cry crz cya cyb cyc cyo cyr cz- czc czo oaa oab oac oao oar ob- oba obb obc obo obr oby oc- oca ocb occ oco ocr ocz oo- ooa oob ooc ooo oor or- ora orb orc oro orr ory orz oya oyo oza ozo ozz ra- raa rab rac rao rar ray raz rba rbb rbc rbo rbr rca rcb rcc rco rcr roa rob roc roo ror roy roz rra rrb rrc rrr ry- rya ryc ryo ryr ryy ryz rza rzb rzo rzy yaa yab yac yao yar yay yaz ybc ybr yby ybz yca ycc yco ycy yob yoc yoo yor yoy yra yrc yro yyb yyc yyy yyz yzb yzr yzy zaa zab zac zao zar zay zaz zbb zbc zbr zby zco zo- zoa zob zoc zoo zor zro zzr zzy zzz