-er a-a a-c aaa aac aae aag aak aar ac- aca acc ace acg ack acr aea aec aee aeg aek aer ag- aga agc age agg agk agr aka akc ake akg akk akr ar- ara arc are arg ark arr c-- caa cac cae cag cak car cca ccc cce ccg cck ccr ce- cea cec cee ceg cek cer cga cgc cge cgg cgr cka ckc cra crc cre crg crk crr eaa eac eae eag eak ear ec- eca ecc ece ecg eck ecr eea eec eee eeg eek eer ega egc ege egg egr eka ekc eke ekg ekr era erc ere erg erk err gaa gac gae gag gak gar gca gcc gce gcg gck gcr ge- gea gec gee geg gek ger gga ggc ggg ggr gka gra grc gre grg grk grr ka- kaa kac kae kag kak kar kca kcc kce kcg kck kcr ke- kea kec kee keg kek ker kga kgc kkc kke kkk kkr kra krc krg krk krr ra- raa rac rae rag rak rar rca rcc rce rcg rcr re- rea rec ree reg rek rer rga rgc rge rgg rgk rgr rkc rke rkg rkk rra rrc rrg rrk rrr