-ic a-a a-b a-c a-i a-t aaa aab aac aai aao aas aat ab- aba abb abc abi abo abs abt ac- aca acb acc aci aco acs act ai- aia aib aic aii aio ais ait aoa aob aoc aoi aoo aos aot as- asa asb asc asi aso ass ast at- ata atb atc ati ato ats att baa bab bac bai bao bas bat bba bbb bbc bbi bbo bbs bbt bca bcb bcc bci bco bcs bct bi- bia bib bic bii bio bis bit boa bob boc boi boo bos bot bsa bsb bsc bsi bso bss bst bta btb btc bti bto bts btt c-- caa cab cac cai cao cas cat cba cbb cbc cbi cbo cbs cbt cca ccb ccc cci cco ccs cct ci- cia cib cic cii cio cis cit co- coa cob coc coi coo cos cot csa csb csc csi cso css cst cta ctb ctc cti cto cts ctt ia- iaa iab iac iai iao ias iat iba ibb ibc ibi ibo ibs ibt ica icb icc ici ico ics ict iia iib iic iii iio iis iit io- ioa iob ioc ioi ioo ios iot is- isa isb isc isi iso iss ist ita itb itc iti ito its itt o-i oaa oab oac oai oao oas oat ob- oba obb obc obi obo obs obt oc- oca ocb occ oci oco ocs oct oia oib oic oii oio ois oit oo- ooa oob ooc ooi ooo oos oot os- osa osb osc osi oso oss ost ot- ota otb otc oti oto ots ott saa sab sac sai sao sas sat sba sbb sbc sbi sbo sbs sbt sca scb scc sci sco scs sct sia sib sic sii sio sis sit soa sob soc soi soo sos sot ss- ssa ssb ssc ssi sso sss sst sta stb stc sti sto sts stt taa tab tac tai tao tas tat tba tbb tbc tbi tbo tbs tbt tca tcb tcc tci tco tcs tct tia tib tic tii tio tis tit to- toa tob toc toi too tos tot tsa tsb tsc tsi tso tss tst tta ttb ttc tti tto tts ttt