a-a a-b a-t aaa aab aao aar aat aav ab- aba abb abo abr abt abv aoa aob aoo aor aot aov ar- ara arb aro arr art arv at- ata atb ato atr att atv av- ava avb avo avr avt baa bab bao bar bat bav bba bbb bbo bbr bbt boa bob boo bor bot bov bra brb bro brr brt brv bta btb bto btr btt btv bva bvb bvo bvr bvt bvv oaa oab oao oar oat oav ob- oba obb obo obr obt obv oo- ooa oob ooo oor oot oov or- ora orb oro orr ort orv ot- ota otb oto otr ott otv ov- ova ovb ovo ovv ra- raa rab rao rar rat rav rba rbb rbo rbr rbt roa rob roo ror rot rov rra rrb rrr rrt rta rtb rto rtr rtt rtv rva rvb rvo rvr rvt rvv taa tab tao tar tat tav tba tbb tbo tbr tbt tbv to- toa tob too tor tot tov tra trb tro trr trt trv tta ttb tto ttr ttt ttv tva tvb tvo tvr tvt v-a vaa vab vao var vat vav vba vbo vbr vbv voa vob voo vor vot vov vra vrb vrr vrt vta vtb vto vtr vtt vtv vva vvb vvo vvr vvt vvv