a-a a-b a-t aaa aab aad aae aaf aas aat ab- aba abb abd abe abf abs abt ad- ada adb add ade adf ads adt aea aeb aed aee aef aes aet af- afa afb afd afe aff afs aft as- asa asb asd ase asf ass ast at- ata atb atd ate atf ats att baa bab bad bae baf bas bat bba bbb bbd bbe bbf bbs bbt bda bdb bdd bde bdf bds bdt be- bea beb bed bee bef bes bet bfa bfb bfd bfe bff bfs bft bsa bsb bsd bse bsf bss bst bta btb btd bte btf bts btt daa dab dad dae daf das dat dba dbb dbd dbe dbf dbs dbt dda ddb ddd dde ddf dds ddt de- dea deb ded dee def des det dfa dfb dfd dfe dff dfs dft dsa dsb dsd dse dsf dss dst dta dtb dtd dte dtf dts dtt eaa eab ead eae eaf eas eat eba ebb ebd ebe ebf ebs ebt ed- eda edb edd ede edf eds edt eea eeb eed eee eef ees eet ef- efa efb efd efe eff efs eft es- esa esb esd ese esf ess est eta etb etd ete etf ets ett faa fab fad fae faf fas fat fba fbb fbd fbe fbf fbs fbt fda fdb fdd fde fdf fds fdt fea feb fed fee fef fes fet ffa ffd ffe fff ffs fft fsa fsb fsd fse fsf fss fst fta ftb ftd fte ftf fts ftt saa sab sad sae saf sas sat sba sbb sbd sbe sbf sbs sbt sda sdb sdd sde sdf sds sdt se- sea seb sed see sef ses set sfa sfb sfd sfe sff sfs sft ss- ssa ssb ssd sse ssf sss sst sta stb std ste stf sts stt taa tab tad tae taf tas tat tba tbb tbd tbe tbf tbs tbt tda tdb tdd tde tdf tds tdt te- tea teb ted tee tef tes tet tfa tfb tfd tfe tff tfs tft tsa tsb tsd tse tsf tss tst tta ttb ttd tte ttf tts ttt