a-a a-b a-c aaa aab aac aag aak aan aar aas ab- aba abb abc abg abk abn abr abs ac- aca acb acc acg ack acn acr acs ag- aga agb agc agg agk agn agr ags aka akb akc akg akk akn akr aks an- ana anb anc ang ank ann anr ans ar- ara arb arc arg ark arn arr ars as- asa asb asc asg ask asn asr ass baa bab bac bag bak ban bar bas bba bbb bbc bbg bbk bbn bbr bbs bca bcb bcc bcg bck bcn bcr bcs bga bgb bgc bgg bgk bgn bgr bgs bka bkb bkc bkg bkk bkn bkr bks bna bnb bnc bng bnk bnn bnr bns bra brb brg brk brn brr brs bsa bsb bsc bsg bsk bsn bsr bss c-- caa cab cac cag cak can car cas cba cbb cbc cbg cbk cbn cbr cbs cca ccb ccc ccg cck ccn ccr ccs cga cgb cgc cgg cgn cgr cgs cka ckb ckc cks cn- cna cnb cnc cng cnn cnr cns cra crb crc crg crk crn crr crs csa csb csc csg csk csn csr css gaa gab gac gag gak gan gar gas gba gbc gbg gbk gbn gbr gbs gca gcb gcc gcg gck gcn gcr gcs gga ggb ggc ggg ggn ggr ggs gka gkb gkn gks gna gnb gnc gnn gnr gns gra grb grc grg grk grn grr grs gsa gsb gsc gsg gsk gsn gsr gss ka- kaa kab kac kag kak kan kar kas kba kbb kbc kbk kbn kbr kbs kca kcb kcc kcg kck kcn kcr kcs kga kgb kgc kgs kkb kkc kkk kkn kkr kks kn- kna knc kng knk knn knr kra krc krg krk krn krr krs ksa ksb ksc ksg ksk ksn ksr kss naa nab nac nag nak nan nar nas nba nbb nbc nbg nbk nbn nbr nbs nca ncb ncc ncg nck ncn ncr ncs nga ngb ngc ngg ngk ngn ngs nka nkc nkk nkn nkr nks nna nnb nnc nng nnk nnn nns nra nrb nrc nrg nrk nrn nrr nrs nsa nsb nsc nsg nsk nsn nsr nss ra- raa rab rac rag rak ran rar ras rba rbb rbc rbg rbk rbn rbr rbs rca rcb rcc rcg rcn rcr rcs rga rgb rgc rgg rgk rgn rgr rgs rkb rkc rkg rkk rks rna rnb rnc rng rnn rnr rns rra rrb rrc rrg rrk rrn rrr rrs rsa rsb rsc rsg rsk rsn rsr rss saa sab sac sag sak san sar sas sba sbb sbc sbg sbk sbn sbr sbs sca scb scc scg sck scn scr scs sga sgb sgc sgg sgk sgn sgr sgs sk- ska skb skc skg skk skr sks sna snb snc sng snk snn snr sns sr- sra srb src srg srk srn srr srs ss- ssa ssb ssc ssg ssk ssn ssr sss