a-a a-b a-i a-t aaa aab aaf aai aao aar aas aat ab- aba abb abf abi abo abr abs abt af- afa afb aff afi afo afr afs aft ai- aia aib aif aii aio air ais ait aoa aob aof aoi aoo aor aos aot ar- ara arb arf ari aro arr ars art as- asa asb asf asi aso asr ass ast at- ata atb atf ati ato atr ats att baa bab baf bai bao bar bas bat bba bbb bbf bbi bbo bbr bbs bbt bfa bfb bff bfi bfo bfr bfs bft bi- bia bib bif bii bio bir bis bit boa bob bof boi boo bor bos bot bra brb brf bri bro brr brs brt bsa bsb bsf bsi bso bsr bss bst bta btb btf bti bto btr bts btt faa fab faf fai fao far fas fat fba fbb fbf fbi fbo fbr fbs fbt ffa fff ffi ffo ffr ffs fft fia fib fif fii fir fis fit foa fob fof foi foo for fos fot fra frb frf fri fro frr frs frt fsa fsb fsf fsi fso fsr fss fst fta ftb ftf fti fto ftr fts ftt i-f ia- iaa iab iaf iai iao iar ias iat iba ibb ibf ibi ibo ibr ibs ibt ifa ifb iff ifi ifo ifr ifs ift iia iib iif iii iio iir iis iit io- ioa iob iof ioi ioo ior ios iot ir- ira irb irf iri iro irr irs irt is- isa isb isf isi iso isr iss ist ita itb itf iti ito its itt o-i oaa oab oaf oai oao oar oas oat ob- oba obb obf obi obo obr obs obt of- ofa ofb off ofi ofo ofr ofs oft oia oib oif oii oio oir ois oit oo- ooa oob oof ooi ooo oor oos oot or- ora orb orf ori oro orr ors ort os- osa osb osf osi oso osr oss ost ot- ota otb otf oti oto otr ots ott ra- raa rab raf rai rao rar ras rat rba rbb rbf rbi rbo rbr rbs rbt rfa rfb rff rfi rfo rfr rfs rft ria rib rif rii rio rir ris rit roa rob rof roi roo ror ros rot rra rrb rrf rri rrr rrs rrt rsa rsb rsf rsi rso rsr rss rst rta rtb rtf rti rto rtr rts rtt saa sab saf sai sao sar sas sat sba sbb sbf sbi sbo sbr sbs sbt sfa sfb sff sfi sfo sfr sfs sft sia sib sif sii sio sir sis sit soa sob sof soi soo sor sos sot sr- sra srb srf sri sro srr srs srt ss- ssa ssb ssf ssi sso ssr sss sst sta stb stf sti sto str sts stt taa tab taf tai tao tar tas tat tba tbb tbf tbi tbo tbr tbs tbt tfa tfb tff tfi tfo tfr tfs tft tia tib tif tii tio tir tis tit to- toa tob tof toi too tor tos tot tra trb trf tri tro trr trs trt tsa tsb tsf tsi tso tsr tss tst tta ttb ttf tti tto ttr tts ttt