a-a a-b a-i a-t aaa aab aaf aai aao aar aat ab- aba abb abf abi abo abr abt af- afa afb aff afi afo afr aft ai- aia aib aif aii aio air ait aoa aob aof aoi aoo aor aot ar- ara arb arf ari aro arr art at- ata atb atf ati ato atr att baa bab baf bai bao bar bat bba bbb bbf bbi bbo bbr bbt bfa bfb bff bfi bfo bfr bft bi- bia bib bif bii bio bir bit boa bob bof boi boo bor bot bra brb brf bri bro brr brt bta btb btf bti bto btr btt faa fab faf fai fao far fat fba fbb fbf fbi fbo fbr fbt ffa fff ffi ffo ffr fft fia fib fif fii fir fit foa fob fof foi foo for fot fra frb frf fri fro frr frt fta ftb ftf fti fto ftr ftt i-f ia- iaa iab iaf iai iao iar iat iba ibb ibf ibi ibo ibr ibt ifa ifb iff ifi ifo ifr ift iia iib iif iii iio iir iit io- ioa iob iof ioi ioo ior iot ir- ira irb irf iri iro irr irt ita itb itf iti ito itt o-i oaa oab oaf oai oao oar oat ob- oba obb obf obi obo obr obt of- ofa ofb off ofi ofo ofr oft oia oib oif oii oio oir oit oo- ooa oob oof ooi ooo oor oot or- ora orb orf ori oro orr ort ot- ota otb otf oti oto otr ott ra- raa rab raf rai rao rar rat rba rbb rbf rbi rbo rbr rbt rfa rfb rff rfi rfo rfr rft ria rib rif rii rio rir rit roa rob rof roi roo ror rot rra rrb rrf rri rrr rrt rta rtb rtf rti rto rtr rtt taa tab taf tai tao tar tat tba tbb tbf tbi tbo tbr tbt tfa tfb tff tfi tfo tfr tft tia tib tif tii tio tir tit to- toa tob tof toi too tor tot tra trb trf tri tro trr trt tta ttb ttf tti tto ttr ttt