a-a a-b aaa aab aah aak aao aar ab- aba abb abh abk abo abr aha ahb ahh ahk aho ahr aka akb akh akk ako akr aoa aob aoh aok aoo aor ar- ara arb arh ark aro arr baa bab bah bak bao bar bba bbb bbh bbk bbo bbr bha bhb bhh bhk bho bhr bka bkb bkk bko bkr boa bob boh bok boo bor bra brb brh brk bro brr haa hab hah hak hao har hba hbb hbh hbk hbo hbr hha hhb hhh hhk hho hhr hka hkb hkh hkk hko hkr hoa hob hoh hok hoo hor hr- hra hrb hrh hrk hro hrr ka- kaa kab kah kak kao kar kba kbb kbh kbk kbo kbr kha khh khk kho khr kkb kkh kkk kkr koa kob koh kok koo kor kra krk kro krr oaa oab oah oak oao oar ob- oba obb obh obk obo obr oha ohh oho ohr oka okb okk oko okr oo- ooa oob ooh ook ooo oor or- ora orb orh ork oro orr ra- raa rab rah rak rao rar rba rbb rbh rbk rbo rbr rh- rha rhb rhh rho rhr rkb rkk rko roa rob roh rok roo ror rra rrb rrh rrk rrr