a-a a-b aaa aab aak aan aao aav ab- aba abb abk abn abo abv aka akb akk akn ako akv an- ana anb ank ann ano anv aoa aob aok aon aoo aov av- ava avb avk avn avo baa bab bak ban bao bav bba bbb bbk bbn bbo bka bkb bkk bkn bko bkv bna bnb bnk bnn bno bnv boa bob bok bon boo bov bva bvb bvk bvn bvo bvv ka- kaa kab kak kan kao kav kba kbb kbk kbn kbo kkb kkk kkn kkv kn- kna knk knn kno koa kob kok kon koo kva kvb kvk kvn kvo kvv naa nab nak nan nao nav nba nbb nbk nbn nbo nbv nka nkk nkn nko nna nnb nnk nnn nno nnv no- noa nob nok non noo nov nva nvb nvk nvn nvv oaa oab oak oan oao oav ob- oba obb obk obn obo obv oka okb okk oko on- ona onb onk onn ono oo- ooa oob ook oon ooo oov ov- ova ovb ovo ovv v-a vaa vab vak van vao vav vba vbk vbo vbv vka vkb vn- vna vno vnv voa vob vok von voo vov vva vvb vvo vvv