a-a a-b a-c aaa aab aac aah aao aas ab- aba abb abc abh abo abs ac- aca acb acc ach aco acs aha ahb ahc ahh aho ahs aoa aob aoc aoh aoo aos as- asa asb asc ash aso ass baa bab bac bah bao bas bba bbb bbc bbh bbo bbs bca bcb bcc bch bco bcs bha bhb bhc bhh bho bhs boa bob boc boh boo bos bsa bsb bsc bsh bso bss c-- caa cab cac cah cao cas cba cbb cbc cbh cbo cbs cca ccb ccc cch cco ccs ch- cha chb chc chh cho chs co- coa cob coc coh coo cos csa csb csc csh cso css haa hab hac hah hao has hba hbb hbc hbh hbo hbs hca hcb hcc hch hco hcs hha hhb hhc hhh hho hhs hoa hob hoc hoh hoo hos hsa hsb hsc hsh hss oaa oab oac oah oao oas ob- oba obb obc obh obo obs oc- oca ocb occ och oco ocs oha ohc ohh oho ohs oo- ooa oob ooc ooh ooo oos os- osa osb osc osh oso oss saa sab sac sah sao sas sba sbb sbc sbh sbo sbs sca scb scc sch sco scs sh- sha shb shc shh sho shs soa sob soc soh soo sos ss- ssa ssb ssc ssh sso sss