a-a a-b aaa aab aaf aan aao aar aav ab- aba abb abf abn abo abr abv af- afa afb aff afn afo afr afv an- ana anb anf ann ano anr anv aoa aob aof aon aoo aor aov ar- ara arb arf arn aro arr arv av- ava avb avf avn avo avr baa bab baf ban bao bar bav bba bbb bbf bbn bbo bbr bfa bfb bff bfn bfo bfr bfv bna bnb bnf bnn bno bnr bnv boa bob bof bon boo bor bov bra brb brf brn bro brr brv bva bvb bvn bvo bvr bvv faa fab faf fan fao far fav fba fbb fbf fbn fbo fbr ffa fff ffn ffo ffr ffv fna fnb fnf fnn fnr fnv foa fob fof fon foo for fra frb frf frn fro frr fva naa nab naf nan nao nar nav nba nbb nbf nbn nbo nbr nbv nfa nfb nff nfn nfo nfr nfv nna nnb nnf nnn nno nnv no- noa nob nof non noo nor nov nra nrb nrf nrn nro nrr nrv nva nvb nvn nvv oaa oab oaf oan oao oar oav ob- oba obb obf obn obo obr obv of- ofa ofb off ofn ofo ofr ofv on- ona onb onf onn ono onr oo- ooa oob oof oon ooo oor oov or- ora orb orf orn oro orr orv ov- ova ovb ovf ovo ovv ra- raa rab raf ran rao rar rav rba rbb rbf rbn rbo rbr rfa rfb rff rfn rfo rfr rfv rna rnb rnn rno rnr rnv roa rob rof ron roo ror rov rra rrb rrf rrn rrr rva rvb rvf rvn rvo rvr rvv v-a vaa vab van vao var vav vba vbo vbr vbv vfa vfb vff vfn vfr vfv vn- vna vnf vno vnr vnv voa vob vof von voo vor vov vra vrb vrf vrn vrr vva vvb vvo vvr vvv