a-a a-b a-i a-t aaa aab aai aak aao aas aat ab- aba abb abi abk abo abs abt ai- aia aib aii aik aio ais ait aka akb aki akk ako aks aoa aob aoi aok aoo aos aot as- asa asb asi ask aso ass ast at- ata atb ati ato ats att baa bab bai bak bao bas bat bba bbb bbi bbk bbo bbs bbt bi- bia bib bii bik bio bis bit bka bkb bkk bko bks bkt boa bob boi bok boo bos bot bsa bsb bsi bsk bso bss bst bta btb bti btk bto bts btt ia- iaa iab iai iao ias iat iba ibb ibi ibk ibo ibs ibt iia iib iii iio iis iit ika ikb iki ikk iko iks ikt io- ioa iob ioi ioo ios iot is- isa isb isi isk iso iss ist ita itb iti itk ito its itt k-t ka- kaa kab kai kak kao kas kat kba kbb kbi kbk kbo kbs kia kib kii kik kio kis kit kkb kki kkk kks kkt koa kob koi kok koo kos kot ksa ksb ksi ksk kso kss kst kta ktb ktk kto kts ktt o-i oaa oab oai oak oao oas oat ob- oba obb obi obk obo obs obt oia oib oii oik oio ois oit oka okb oki okk oko oks oo- ooa oob ooi ook ooo oos oot os- osa osb osi osk oso oss ost ot- ota otb oti otk oto ots ott saa sab sai sak sao sas sat sba sbb sbi sbk sbo sbs sbt sia sib sii sik sio sis sit sk- ska skb ski skk sko sks skt soa sob soi sok soo sos sot ss- ssa ssb ssi ssk sso sss sst sta stb sti stk sto sts stt taa tab tai tak tao tas tat tba tbb tbi tbk tbo tbs tbt tia tib tii tik tio tis tit tka tkb tkk tko tks tkt to- toa tob toi tok too tos tot tsa tsb tsi tsk tso tss tst tta ttb tti ttk tto tts ttt