a-a a-b a-i a-t aaa aab aai aan aao aas aat ab- aba abb abi abn abo abs abt ai- aia aib aii ain aio ais ait an- ana anb ani ann ano ans ant aoa aob aoi aon aoo aos aot as- asa asb asi asn aso ass ast at- ata atb ati atn ato ats att baa bab bai ban bao bas bat bba bbb bbi bbn bbo bbs bbt bi- bia bib bii bin bio bis bit bna bnb bni bnn bno bns bnt boa bob boi bon boo bos bot bsa bsb bsi bsn bso bss bst bta btb bti btn bto bts btt ia- iaa iab iai ian iao ias iat iba ibb ibi ibn ibo ibs ibt iia iib iii iin iio iis iit in- ina inb ini inn ino ins int io- ioa iob ioi ion ioo ios iot is- isa isb isi isn iso iss ist ita itb iti itn ito its itt n-i naa nab nai nan nao nas nat nba nbb nbi nbn nbo nbs nbt nia nib nii nin nio nis nit nna nnb nni nnn nno nns nnt no- noa nob noi non noo nos not nsa nsb nsi nsn nso nss nst nta ntb nti ntn nto nts ntt o-i oaa oab oai oan oao oas oat ob- oba obb obi obn obo obs obt oia oib oii oin oio ois oit on- ona onb oni onn ono ons ont oo- ooa oob ooi oon ooo oos oot os- osa osb osi osn oso oss ost ot- ota otb oti otn oto ots ott saa sab sai san sao sas sat sba sbb sbi sbn sbo sbs sbt sia sib sii sin sio sis sit sna snb sni snn sno sns snt soa sob soi son soo sos sot ss- ssa ssb ssi ssn sso sss sst sta stb sti stn sto sts stt taa tab tai tan tao tas tat tba tbb tbi tbn tbo tbs tbt tia tib tii tin tio tis tit tna tnb tni tnn tno tns tnt to- toa tob toi ton too tos tot tsa tsb tsi tsn tso tss tst tta ttb tti ttn tto tts ttt