a-a a-b aaa aab aak aan aao aar aav ab- aba abb abk abn abo abr abv aka akb akk akn ako akr akv an- ana anb ank ann ano anr anv aoa aob aok aon aoo aor aov ar- ara arb ark arn aro arr arv av- ava avb avk avn avo avr baa bab bak ban bao bar bav bba bbb bbk bbn bbo bbr bka bkb bkk bkn bko bkr bkv bna bnb bnk bnn bno bnr bnv boa bob bok bon boo bor bov bra brb brk brn bro brr brv bva bvb bvk bvn bvo bvr bvv ka- kaa kab kak kan kao kar kav kba kbb kbk kbn kbo kbr kkb kkk kkn kkr kkv kn- kna knk knn kno knr koa kob kok kon koo kor kra krk krn kro krr krv kva kvb kvk kvn kvo kvr kvv naa nab nak nan nao nar nav nba nbb nbk nbn nbo nbr nbv nka nkk nkn nko nkr nna nnb nnk nnn nno nnv no- noa nob nok non noo nor nov nra nrb nrk nrn nro nrr nrv nva nvb nvk nvn nvv oaa oab oak oan oao oar oav ob- oba obb obk obn obo obr obv oka okb okk oko okr on- ona onb onk onn ono onr oo- ooa oob ook oon ooo oor oov or- ora orb ork orn oro orr orv ov- ova ovb ovo ovv ra- raa rab rak ran rao rar rav rba rbb rbk rbn rbo rbr rkb rkk rko rkv rna rnb rnn rno rnr rnv roa rob rok ron roo ror rov rra rrb rrk rrn rrr rva rvb rvn rvo rvr rvv v-a vaa vab vak van vao var vav vba vbk vbo vbr vbv vka vkb vn- vna vno vnr vnv voa vob vok von voo vor vov vra vrb vrk vrn vrr vva vvb vvo vvr vvv