a-a a-b a-i a-t aaa aab aai aao aas aat ab- aba abb abi abo abs abt ai- aia aib aii aio ais ait aoa aob aoi aoo aos aot as- asa asb asi aso ass ast at- ata atb ati ato ats att baa bab bai bao bas bat bba bbb bbi bbo bbs bbt bi- bia bib bii bio bis bit boa bob boi boo bos bot bsa bsb bsi bso bss bst bta btb bti bto bts btt ia- iaa iab iai iao ias iat iba ibb ibi ibo ibs ibt iia iib iii iio iis iit io- ioa iob ioi ioo ios iot is- isa isb isi iso iss ist ita itb iti ito its itt o-i oaa oab oai oao oas oat ob- oba obb obi obo obs obt oia oib oii oio ois oit oo- ooa oob ooi ooo oos oot os- osa osb osi oso oss ost ot- ota otb oti oto ots ott saa sab sai sao sas sat sba sbb sbi sbo sbs sbt sia sib sii sio sis sit soa sob soi soo sos sot ss- ssa ssb ssi sso sss sst sta stb sti sto sts stt taa tab tai tao tas tat tba tbb tbi tbo tbs tbt tia tib tii tio tis tit to- toa tob toi too tos tot tsa tsb tsi tso tss tst tta ttb tti tto tts ttt