a-a a-b aaa aab aan aao aar aav ab- aba abb abn abo abr abv an- ana anb ann ano anr anv aoa aob aon aoo aor aov ar- ara arb arn aro arr arv av- ava avb avn avo avr baa bab ban bao bar bav bba bbb bbn bbo bbr bna bnb bnn bno bnr bnv boa bob bon boo bor bov bra brb brn bro brr brv bva bvb bvn bvo bvr bvv naa nab nan nao nar nav nba nbb nbn nbo nbr nbv nna nnb nnn nno nnv no- noa nob non noo nor nov nra nrb nrn nro nrr nrv nva nvb nvn nvv oaa oab oan oao oar oav ob- oba obb obn obo obr obv on- ona onb onn ono onr oo- ooa oob oon ooo oor oov or- ora orb orn oro orr orv ov- ova ovb ovo ovv ra- raa rab ran rao rar rav rba rbb rbn rbo rbr rna rnb rnn rno rnr rnv roa rob ron roo ror rov rra rrb rrn rrr rva rvb rvn rvo rvr rvv v-a vaa vab van vao var vav vba vbo vbr vbv vn- vna vno vnr vnv voa vob von voo vor vov vra vrb vrn vrr vva vvb vvo vvr vvv