a-a a-b aaa aab aae aak aao aav ab- aba abb abe abk abo abv aea aeb aee aek aeo aev aka akb ake akk ako akv aoa aob aoe aok aoo aov av- ava avb ave avk avo baa bab bae bak bao bav bba bbb bbe bbk bbo be- bea beb bee bek beo bev bka bkb bke bkk bko bkv boa bob boe bok boo bov bva bvb bve bvk bvo bvv eaa eab eae eak eao eav eba ebb ebe ebk ebo ebv eea eeb eee eek eeo eev eka ekb eke eko ekv eo- eoa eob eoe eok eoo eva evb eve evo evv ka- kaa kab kae kak kao kav kba kbb kbe kbk kbo ke- kea keb kee kek keo kev kkb kke kkk kkv koa kob koe kok koo kva kvb kvk kvo kvv oaa oab oae oak oao oav ob- oba obb obe obk obo obv oea oeb oee oeo oka okb oke okk oko oo- ooa oob ook ooo oov ov- ova ovb ove ovo ovv v-a v-e vaa vab vae vak vao vav vba vbk vbo vbv vea veb vee vek veo vka vkb voa vob voe vok voo vov vva vvb vvo vvv