-er a-a a-b aaa aab aae aao aar aav ab- aba abb abe abo abr abv aea aeb aee aeo aer aev aoa aob aoe aoo aor aov ar- ara arb are aro arr arv av- ava avb ave avo avr baa bab bae bao bar bav bba bbb bbe bbo bbr be- bea beb bee beo ber bev boa bob boe boo bor bov bra brb bre bro brr brv bva bvb bve bvo bvr bvv eaa eab eae eao ear eav eba ebb ebe ebo ebr ebv eea eeb eee eeo eer eev eo- eoa eob eoe eoo eor era erb ere ero err erv eva evb eve evo evr evv oaa oab oae oao oar oav ob- oba obb obe obo obr obv oea oeb oee oeo oer oo- ooa oob ooo oor oov or- ora orb ore oro orr orv ov- ova ovb ove ovo ovv ra- raa rab rae rao rar rav rba rbb rbe rbo rbr re- rea reb ree reo rer rev roa rob roe roo ror rov rra rrb rrr rva rvb rve rvo rvr rvv v-a v-e vaa vab vae vao var vav vba vbo vbr vbv vea veb vee veo ver voa vob voe voo vor vov vra vrb vre vrr vva vvb vvo vvr vvv