a-a a-b a-c a-z aaa aab aac aar aay aaz ab- aba abb abc abr aby abz ac- aca acb acc acr acy acz ar- ara arb arc arr ary arz ay- aya ayc ayr ayz az- aza azb azy azz baa bab bac bar bay baz bba bbb bbc bbr bby bca bcb bcc bcr bcy bcz bra brb brr bry brz by- bya byc byr byz bza bzr bzz c-- caa cab cac car cay caz cba cbb cbc cbr cby cbz cca ccb ccc ccr ccz cra crb crc crr cry crz cya cyb cyc cyr cz- czc ra- raa rab rac rar ray raz rba rbb rbc rbr rca rcb rcc rcr rra rrb rrc rrr ry- rya ryc ryr ryy ryz rza rzb rzy yaa yab yac yar yay yaz ybc ybr yby ybz yca ycc ycy yra yrc yyb yyc yyy yyz yzb yzr yzy zaa zab zac zar zay zaz zbb zbc zbr zby zzr zzy zzz