-er a-a a-c aaa aac aae aak aan aar ac- aca acc ace ack acn acr aea aec aee aek aen aer aka akc ake akk akn akr an- ana anc ane ank ann anr ar- ara arc are ark arn arr c-- caa cac cae cak can car cca ccc cce cck ccn ccr ce- cea cec cee cek cen cer cka ckc cn- cna cnc cne cnn cnr cra crc cre crk crn crr eaa eac eae eak ean ear ec- eca ecc ece eck ecn ecr eea eec eee eek een eer eka ekc eke ekr en- ena enc ene enk enn enr era erc ere erk ern err ka- kaa kac kae kak kan kar kca kcc kce kck kcn kcr ke- kea kec kee kek ken ker kkc kke kkk kkn kkr kn- kna knc kne knk knn knr kra krc krk krn krr naa nac nae nak nan nar nca ncc nce nck ncn ncr ne- nea nec nee nek nen ner nka nkc nke nkk nkn nkr nna nnc nne nnk nnn nra nrc nre nrk nrn nrr ra- raa rac rae rak ran rar rca rcc rce rcn rcr re- rea rec ree rek ren rer rkc rke rkk rna rnc rnn rnr rra rrc rrk rrn rrr