a-a a-b a-c a-t aaa aab aac aan aar aas aat ab- aba abb abc abn abr abs abt ac- aca acb acc acn acr acs act an- ana anb anc ann anr ans ant ar- ara arb arc arn arr ars art as- asa asb asc asn asr ass ast at- ata atb atc atn atr ats att baa bab bac ban bar bas bat bba bbb bbc bbn bbr bbs bbt bca bcb bcc bcn bcr bcs bct bna bnb bnc bnn bnr bns bnt bra brb brn brr brs brt bsa bsb bsc bsn bsr bss bst bta btb btc btn btr bts btt c-- caa cab cac can car cas cat cba cbb cbc cbn cbr cbs cbt cca ccb ccc ccn ccr ccs cct cn- cna cnb cnc cnn cnr cns cnt cra crb crc crn crr crs crt csa csb csc csn csr css cst cta ctb ctc ctn ctr cts ctt naa nab nac nan nar nas nat nba nbb nbc nbn nbr nbs nbt nca ncb ncc ncn ncr ncs nct nna nnb nnc nnn nns nnt nra nrb nrc nrn nrr nrs nrt nsa nsb nsc nsn nsr nss nst nta ntb ntc ntn ntr nts ntt ra- raa rab rac ran rar ras rat rba rbb rbc rbn rbr rbs rbt rca rcb rcc rcn rcr rcs rct rna rnb rnc rnn rnr rns rnt rra rrb rrc rrn rrr rrs rrt rsa rsb rsc rsn rsr rss rst rta rtb rtc rtn rtr rts rtt saa sab sac san sar sas sat sba sbb sbc sbn sbr sbs sbt sca scb scc scn scr scs sct sna snb snc snn snr sns snt sr- sra srb src srn srr srs srt ss- ssa ssb ssc ssn ssr sss sst sta stb stc stn str sts stt taa tab tac tan tar tas tat tba tbb tbc tbn tbr tbs tbt tca tcb tcc tcn tcr tcs tct tna tnb tnc tnn tnr tns tnt tra trb trc trn trr trs trt tsa tsb tsc tsn tsr tss tst tta ttb ttc ttn ttr tts ttt