a-a a-b a-t aaa aab aae aaf aao aas aat ab- aba abb abe abf abo abs abt aea aeb aee aef aeo aes aet af- afa afb afe aff afo afs aft aoa aob aoe aof aoo aos aot as- asa asb ase asf aso ass ast at- ata atb ate atf ato ats att baa bab bae baf bao bas bat bba bbb bbe bbf bbo bbs bbt be- bea beb bee bef beo bes bet bfa bfb bfe bff bfo bfs bft boa bob boe bof boo bos bot bsa bsb bse bsf bso bss bst bta btb bte btf bto bts btt eaa eab eae eaf eao eas eat eba ebb ebe ebf ebo ebs ebt eea eeb eee eef eeo ees eet ef- efa efb efe eff efo efs eft eo- eoa eob eoe eof eoo eos eot es- esa esb ese esf eso ess est eta etb ete etf eto ets ett faa fab fae faf fao fas fat fba fbb fbe fbf fbo fbs fbt fea feb fee fef feo fes fet ffa ffe fff ffo ffs fft foa fob foe fof foo fos fot fsa fsb fse fsf fso fss fst fta ftb fte ftf fto fts ftt oaa oab oae oaf oao oas oat ob- oba obb obe obf obo obs obt oea oeb oee oef oeo oes oet of- ofa ofb ofe off ofo ofs oft oo- ooa oob oof ooo oos oot os- osa osb ose osf oso oss ost ot- ota otb ote otf oto ots ott saa sab sae saf sao sas sat sba sbb sbe sbf sbo sbs sbt se- sea seb see sef seo ses set sfa sfb sfe sff sfo sfs sft soa sob soe sof soo sos sot ss- ssa ssb sse ssf sso sss sst sta stb ste stf sto sts stt taa tab tae taf tao tas tat tba tbb tbe tbf tbo tbs tbt te- tea teb tee tef teo tes tet tfa tfb tfe tff tfo tfs tft to- toa tob toe tof too tos tot tsa tsb tse tsf tso tss tst tta ttb tte ttf tto tts ttt