-er a-a a-c aaa aac aae aak aap aar ac- aca acc ace ack acp acr aea aec aee aek aep aer aka akc ake akk akp akr ap- apa apc ape apk app apr ar- ara arc are ark arp arr c-- caa cac cae cak cap car cca ccc cce cck ccp ccr ce- cea cec cee cek cep cer cka ckc cpa cpc cpe cpk cpp cpr cra crc cre crk crp crr eaa eac eae eak eap ear ec- eca ecc ece eck ecr eea eec eee eek eep eer eka ekc eke ekp ekr ep- epa epc epe epp epr era erc ere erk erp err ka- kaa kac kae kak kap kar kca kcc kce kck kcp kcr ke- kea kec kee kek kep ker kkc kke kkk kkp kkr kpa kpc kpe kpk kpp kpr kra krc krk krp krr p-p paa pac pae pak pap par pca pcc pce pck pcp pcr pea pec pee pek pep per pka pkc pke pkp pkr ppa ppc ppe ppk ppp ppr pra prc pre prk prp prr ra- raa rac rae rak rap rar rca rcc rce rcp rcr re- rea rec ree rek rep rer rkc rke rkk rkp rpa rpc rpe rpk rpp rpr rra rrc rrk rrp rrr