a-a a-b a-t aaa aab aan aar aas aat ab- aba abb abn abr abs abt an- ana anb ann anr ans ant ar- ara arb arn arr ars art as- asa asb asn asr ass ast at- ata atb atn atr ats att baa bab ban bar bas bat bba bbb bbn bbr bbs bbt bna bnb bnn bnr bns bnt bra brb brn brr brs brt bsa bsb bsn bsr bss bst bta btb btn btr bts btt naa nab nan nar nas nat nba nbb nbn nbr nbs nbt nna nnb nnn nns nnt nra nrb nrn nrr nrs nrt nsa nsb nsn nsr nss nst nta ntb ntn ntr nts ntt ra- raa rab ran rar ras rat rba rbb rbn rbr rbs rbt rna rnb rnn rnr rns rnt rra rrb rrn rrr rrs rrt rsa rsb rsn rsr rss rst rta rtb rtn rtr rts rtt saa sab san sar sas sat sba sbb sbn sbr sbs sbt sna snb snn snr sns snt sr- sra srb srn srr srs srt ss- ssa ssb ssn ssr sss sst sta stb stn str sts stt taa tab tan tar tas tat tba tbb tbn tbr tbs tbt tna tnb tnn tnr tns tnt tra trb trn trr trs trt tsa tsb tsn tsr tss tst tta ttb ttn ttr tts ttt