a-a a-b aaa aab aah aao aar aas ab- aba abb abh abo abr abs aha ahb ahh aho ahr ahs aoa aob aoh aoo aor aos ar- ara arb arh aro arr ars as- asa asb ash aso asr ass baa bab bah bao bar bas bba bbb bbh bbo bbr bbs bha bhb bhh bho bhr bhs boa bob boh boo bor bos bra brb brh bro brr brs bsa bsb bsh bso bsr bss haa hab hah hao har has hba hbb hbh hbo hbr hbs hha hhb hhh hho hhr hhs hoa hob hoh hoo hor hos hr- hra hrb hrh hro hrr hrs hsa hsb hsh hsr hss oaa oab oah oao oar oas ob- oba obb obh obo obr obs oha ohh oho ohr ohs oo- ooa oob ooh ooo oor oos or- ora orb orh oro orr ors os- osa osb osh oso osr oss ra- raa rab rah rao rar ras rba rbb rbh rbo rbr rbs rh- rha rhb rhh rho rhr rhs roa rob roh roo ror ros rra rrb rrh rrr rrs rsa rsb rsh rso rsr rss saa sab sah sao sar sas sba sbb sbh sbo sbr sbs sh- sha shb shh sho shr shs soa sob soh soo sor sos sr- sra srb srh sro srr srs ss- ssa ssb ssh sso ssr sss