a-a a-b a-c aaa aab aac aam aao aay ab- aba abb abc abm abo aby ac- aca acb acc acm aco acy ama amb amc amm amo amy aoa aob aoc aom aoo ay- aya ayc ayo baa bab bac bam bao bay bba bbb bbc bbm bbo bby bca bcb bcc bcm bco bcy bma bmb bmc bmm bmo boa bob boc bom boo boy by- bya byc bym byo c-- caa cab cac cam cao cay cba cbb cbc cbm cbo cby cca ccb ccc ccm cco cma cmb cmc cmm cmo cmy co- coa cob coc com coo coy cya cyb cyc cym cyo m-o maa mab mac mam mao may mba mbb mbc mbm mbo mc- mca mcb mcc mcm mco mma mmb mmc mmm mmo moa mob moc mom moo moy my- mya myb myc mym myo oaa oab oac oam oao ob- oba obb obc obm obo oby oc- oca ocb occ ocm oco om- oma omb omc omm omo omy oo- ooa oob ooc oom ooo oya oyo yaa yab yac yam yao yay ybc ybm yby yca ycc yco ycy yma ymc ymm ymo yob yoc yom yoo yoy yyb yyc yyy