-er a-a a-c aaa aac aae aag aak aar aas ac- aca acc ace acg ack acr acs aea aec aee aeg aek aer aes ag- aga agc age agg agk agr ags aka akc ake akg akk akr aks ar- ara arc are arg ark arr ars as- asa asc ase asg ask asr ass c-- caa cac cae cag cak car cas cca ccc cce ccg cck ccr ccs ce- cea cec cee ceg cek cer ces cga cgc cge cgg cgr cgs cka ckc cks cra crc cre crg crk crr crs csa csc cse csg csk csr css eaa eac eae eag eak ear eas ec- eca ecc ece ecg eck ecr ecs eea eec eee eeg eek eer ees ega egc ege egg egr egs eka ekc eke ekg ekr eks era erc ere erg erk err ers es- esa esc ese esg esk esr ess gaa gac gae gag gak gar gas gca gcc gce gcg gck gcr gcs ge- gea gec gee geg gek ger ges gga ggc ggg ggr ggs gka gks gra grc gre grg grk grr grs gsa gsc gse gsg gsk gsr gss ka- kaa kac kae kag kak kar kas kca kcc kce kcg kck kcr kcs ke- kea kec kee keg kek ker kes kga kgc kgs kkc kke kkk kkr kks kra krc krg krk krr krs ksa ksc kse ksg ksk ksr kss ra- raa rac rae rag rak rar ras rca rcc rce rcg rcr rcs re- rea rec ree reg rek rer res rga rgc rge rgg rgk rgr rgs rkc rke rkg rkk rks rra rrc rrg rrk rrr rrs rsa rsc rse rsg rsk rsr rss saa sac sae sag sak sar sas sca scc sce scg sck scr scs se- sea sec see seg sek ser ses sga sgc sge sgg sgk sgr sgs sk- ska skc ske skg skk skr sks sr- sra src sre srg srk srr srs ss- ssa ssc sse ssg ssk ssr sss