-er a-a a-c aaa aac aae aag aak aan aar ac- aca acc ace acg ack acn acr aea aec aee aeg aek aen aer ag- aga agc age agg agk agn agr aka akc ake akg akk akn akr an- ana anc ane ang ank ann anr ar- ara arc are arg ark arn arr c-- caa cac cae cag cak can car cca ccc cce ccg cck ccn ccr ce- cea cec cee ceg cek cen cer cga cgc cge cgg cgn cgr cka ckc cn- cna cnc cne cng cnn cnr cra crc cre crg crk crn crr eaa eac eae eag eak ean ear ec- eca ecc ece ecg eck ecn ecr eea eec eee eeg eek een eer ega egc ege egg egn egr eka ekc eke ekg ekr en- ena enc ene eng enk enn enr era erc ere erg erk ern err gaa gac gae gag gak gan gar gca gcc gce gcg gck gcn gcr ge- gea gec gee geg gek gen ger gga ggc ggg ggn ggr gka gkn gna gnc gne gnn gnr gra grc gre grg grk grn grr ka- kaa kac kae kag kak kan kar kca kcc kce kcg kck kcn kcr ke- kea kec kee keg kek ken ker kga kgc kkc kke kkk kkn kkr kn- kna knc kne kng knk knn knr kra krc krg krk krn krr naa nac nae nag nak nan nar nca ncc nce ncg nck ncn ncr ne- nea nec nee neg nek nen ner nga ngc nge ngg ngk ngn nka nkc nke nkk nkn nkr nna nnc nne nng nnk nnn nra nrc nre nrg nrk nrn nrr ra- raa rac rae rag rak ran rar rca rcc rce rcg rcn rcr re- rea rec ree reg rek ren rer rga rgc rge rgg rgk rgn rgr rkc rke rkg rkk rna rnc rng rnn rnr rra rrc rrg rrk rrn rrr