a-a a-b a-c aaa aab aac aah aao aay ab- aba abb abc abh abo aby ac- aca acb acc ach aco acy aha ahb ahc ahh aho ahy aoa aob aoc aoh aoo ay- aya ayc ayh ayo baa bab bac bah bao bay bba bbb bbc bbh bbo bby bca bcb bcc bch bco bcy bha bhb bhc bhh bho boa bob boc boh boo boy by- bya byc byh byo c-- caa cab cac cah cao cay cba cbb cbc cbh cbo cby cca ccb ccc cch cco ch- cha chb chc chh cho chy co- coa cob coc coh coo coy cya cyb cyc cyo haa hab hac hah hao hay hba hbb hbc hbh hbo hby hca hcb hcc hch hco hcy hha hhb hhc hhh hho hhy hoa hob hoc hoh hoo hoy hy- hya hyb hyc hyh hyo hyy oaa oab oac oah oao ob- oba obb obc obh obo oby oc- oca ocb occ och oco oha ohc ohh oho oo- ooa oob ooc ooh ooo oya oyo yaa yab yac yah yao yay ybc yby yca ycc ych yco ycy yha yhc yob yoc yoo yoy yyb yyc yyy