a-a a-b a-t aaa aab aae aao aas aat ab- aba abb abe abo abs abt aea aeb aee aeo aes aet aoa aob aoe aoo aos aot as- asa asb ase aso ass ast at- ata atb ate ato ats att baa bab bae bao bas bat bba bbb bbe bbo bbs bbt be- bea beb bee beo bes bet boa bob boe boo bos bot bsa bsb bse bso bss bst bta btb bte bto bts btt eaa eab eae eao eas eat eba ebb ebe ebo ebs ebt eea eeb eee eeo ees eet eo- eoa eob eoe eoo eos eot es- esa esb ese eso ess est eta etb ete eto ets ett oaa oab oae oao oas oat ob- oba obb obe obo obs obt oea oeb oee oeo oes oet oo- ooa oob ooo oos oot os- osa osb ose oso oss ost ot- ota otb ote oto ots ott saa sab sae sao sas sat sba sbb sbe sbo sbs sbt se- sea seb see seo ses set soa sob soe soo sos sot ss- ssa ssb sse sso sss sst sta stb ste sto sts stt taa tab tae tao tas tat tba tbb tbe tbo tbs tbt te- tea teb tee teo tes tet to- toa tob toe too tos tot tsa tsb tse tso tss tst tta ttb tte tto tts ttt