a-a a-b a-c aaa aab aac aah aak aao aar ab- aba abb abc abh abk abo abr ac- aca acb acc ach ack aco acr aha ahb ahc ahh ahk aho ahr aka akb akc akh akk ako akr aoa aob aoc aoh aok aoo aor ar- ara arb arc arh ark aro arr baa bab bac bah bak bao bar bba bbb bbc bbh bbk bbo bbr bca bcb bcc bch bck bco bcr bha bhb bhc bhh bhk bho bhr bka bkb bkc bkk bko bkr boa bob boc boh bok boo bor bra brb brh brk bro brr c-- caa cab cac cah cak cao car cba cbb cbc cbh cbk cbo cbr cca ccb ccc cch cck cco ccr ch- cha chb chc chh chk cho chr cka ckb ckc ckh cko co- coa cob coc coh cok coo cor cra crb crc crh crk cro crr haa hab hac hah hak hao har hba hbb hbc hbh hbk hbo hbr hca hcb hcc hch hck hco hcr hha hhb hhc hhh hhk hho hhr hka hkb hkh hkk hko hkr hoa hob hoc hoh hok hoo hor hr- hra hrb hrc hrh hrk hro hrr ka- kaa kab kac kah kak kao kar kba kbb kbc kbh kbk kbo kbr kca kcb kcc kch kck kcr kha khh khk kho khr kkb kkc kkh kkk kkr koa kob koc koh kok koo kor kra krc krk kro krr oaa oab oac oah oak oao oar ob- oba obb obc obh obk obo obr oc- oca ocb occ och ock oco ocr oha ohc ohh oho ohr oka okb okc okk oko okr oo- ooa oob ooc ooh ook ooo oor or- ora orb orc orh ork oro orr ra- raa rab rac rah rak rao rar rba rbb rbc rbh rbk rbo rbr rca rcb rcc rch rco rcr rh- rha rhb rhc rhh rho rhr rkb rkc rkk rko roa rob roc roh rok roo ror rra rrb rrc rrh rrk rrr