-ic a-a a-b a-c a-i a-t aaa aab aac aai aas aat aay ab- aba abb abc abi abs abt aby ac- aca acb acc aci acs act acy ai- aia aib aic aii ais ait aiy as- asa asb asc asi ass ast asy at- ata atb atc ati ats att ay- aya ayc ayi ays ayt baa bab bac bai bas bat bay bba bbb bbc bbi bbs bbt bby bca bcb bcc bci bcs bct bcy bi- bia bib bic bii bis bit biy bsa bsb bsc bsi bss bst bsy bta btb btc bti bts btt bty by- bya byc byi bys byt c-- caa cab cac cai cas cat cay cba cbb cbc cbi cbs cbt cby cca ccb ccc cci ccs cct ci- cia cib cic cii cis cit csa csb csc csi css cst csy cta ctb ctc cti cts ctt cty cya cyb cyc cys cyt ia- iaa iab iac iai ias iat iba ibb ibc ibi ibs ibt iby ica icb icc ici ics ict icy iia iib iic iii iis iit is- isa isb isc isi iss ist isy ita itb itc iti its itt ity iya iyc iys iyt iyy saa sab sac sai sas sat say sba sbb sbc sbi sbs sbt sby sca scb scc sci scs sct sia sib sic sii sis sit ss- ssa ssb ssc ssi sss sst sta stb stc sti sts stt sty sy- sya syb syc syi sys syt taa tab tac tai tas tat tay tba tbb tbc tbi tbs tbt tca tcb tcc tci tcs tct tia tib tic tii tis tit tiy tsa tsb tsc tsi tss tst tsy tta ttb ttc tti tts ttt tty tya tyc tys tyt yaa yab yac yai yas yat yay ybc ybi ybs yby yca ycc yci ycs ycy yii yis yit ysa ysb ysc ysi yss yst ysy yta ytc yts ytt yyb yyc yys yyt yyy