-ic a-a a-b a-c a-i a-t aaa aab aac aai aar aas aat ab- aba abb abc abi abr abs abt ac- aca acb acc aci acr acs act ai- aia aib aic aii air ais ait ar- ara arb arc ari arr ars art as- asa asb asc asi asr ass ast at- ata atb atc ati atr ats att baa bab bac bai bar bas bat bba bbb bbc bbi bbr bbs bbt bca bcb bcc bci bcr bcs bct bi- bia bib bic bii bir bis bit bra brb bri brr brs brt bsa bsb bsc bsi bsr bss bst bta btb btc bti btr bts btt c-- caa cab cac cai car cas cat cba cbb cbc cbi cbr cbs cbt cca ccb ccc cci ccr ccs cct ci- cia cib cic cii cir cis cit cra crb crc cri crr crs crt csa csb csc csi csr css cst cta ctb ctc cti ctr cts ctt ia- iaa iab iac iai iar ias iat iba ibb ibc ibi ibr ibs ibt ica icb icc ici icr ics ict iia iib iic iii iir iis iit ir- ira irb irc iri irr irs irt is- isa isb isc isi isr iss ist ita itb itc iti its itt ra- raa rab rac rai rar ras rat rba rbb rbc rbi rbr rbs rbt rca rcb rcc rci rcr rcs rct ria rib ric rii rir ris rit rra rrb rrc rri rrr rrs rrt rsa rsb rsc rsi rsr rss rst rta rtb rtc rti rtr rts rtt saa sab sac sai sar sas sat sba sbb sbc sbi sbr sbs sbt sca scb scc sci scr scs sct sia sib sic sii sir sis sit sr- sra srb src sri srr srs srt ss- ssa ssb ssc ssi ssr sss sst sta stb stc sti str sts stt taa tab tac tai tar tas tat tba tbb tbc tbi tbr tbs tbt tca tcb tcc tci tcr tcs tct tia tib tic tii tir tis tit tra trb trc tri trr trs trt tsa tsb tsc tsi tsr tss tst tta ttb ttc tti ttr tts ttt