a-a a-b a-c aaa aab aac aah aak aan aao aar ab- aba abb abc abh abk abn abo abr ac- aca acb acc ach ack acn aco acr aha ahb ahc ahh ahk ahn aho ahr aka akb akc akh akk akn ako akr an- ana anb anc anh ank ann ano anr aoa aob aoc aoh aok aon aoo aor ar- ara arb arc arh ark arn aro arr baa bab bac bah bak ban bao bar bba bbb bbc bbh bbk bbn bbo bbr bca bcb bcc bch bck bcn bco bcr bha bhb bhc bhh bhk bho bhr bka bkb bkc bkk bkn bko bkr bna bnb bnc bnk bnn bno bnr boa bob boc boh bok bon boo bor bra brb brh brk brn bro brr c-- caa cab cac cah cak can cao car cba cbb cbc cbh cbk cbn cbo cbr cca ccb ccc cch cck ccn cco ccr ch- cha chb chc chh chk chn cho chr cka ckb ckc ckh cko cn- cna cnb cnc cnh cnn cno cnr co- coa cob coc coh cok con coo cor cra crb crc crh crk crn cro crr haa hab hac hah hak han hao har hba hbb hbc hbh hbk hbn hbo hbr hca hcb hcc hch hck hcn hco hcr hha hhb hhc hhh hhk hhn hho hhr hka hkb hkh hkk hkn hko hkr hna hnb hnc hnh hnk hnn hno hoa hob hoc hoh hok hon hoo hor hr- hra hrb hrc hrh hrk hrn hro hrr ka- kaa kab kac kah kak kan kao kar kba kbb kbc kbh kbk kbn kbo kbr kca kcb kcc kch kck kcn kcr kha khh khk khn kho khr kkb kkc kkh kkk kkn kkr kn- kna knc knk knn kno knr koa kob koc koh kok kon koo kor kra krc krk krn kro krr naa nab nac nah nak nan nao nar nba nbb nbc nbk nbn nbo nbr nca ncb ncc nch nck ncn nco ncr nha nhb nhc nhh nhk nhn nhr nka nkc nkk nkn nko nkr nna nnb nnc nnh nnk nnn nno no- noa nob noc noh nok non noo nor nra nrb nrc nrk nrn nro nrr oaa oab oac oah oak oan oao oar ob- oba obb obc obh obk obn obo obr oc- oca ocb occ och ock ocn oco ocr oha ohc ohh ohn oho ohr oka okb okc okk oko okr on- ona onb onc onh onk onn ono onr oo- ooa oob ooc ooh ook oon ooo oor or- ora orb orc orh ork orn oro orr ra- raa rab rac rah rak ran rao rar rba rbb rbc rbh rbk rbn rbo rbr rca rcb rcc rch rcn rco rcr rh- rha rhb rhc rhh rhn rho rhr rkb rkc rkk rko rna rnb rnc rnh rnn rno rnr roa rob roc roh rok ron roo ror rra rrb rrc rrh rrk rrn rrr