-er a-a a-c aaa aac aae aak aap aar aas ac- aca acc ace ack acp acr acs aea aec aee aek aep aer aes aka akc ake akk akp akr aks ap- apa apc ape apk app apr aps ar- ara arc are ark arp arr ars as- asa asc ase ask asp asr ass c-- caa cac cae cak cap car cas cca ccc cce cck ccp ccr ccs ce- cea cec cee cek cep cer ces cka ckc cks cpa cpc cpe cpk cpp cpr cps cra crc cre crk crp crr crs csa csc cse csk csp csr css eaa eac eae eak eap ear eas ec- eca ecc ece eck ecr ecs eea eec eee eek eep eer ees eka ekc eke ekp ekr eks ep- epa epc epe epp epr eps era erc ere erk erp err ers es- esa esc ese esk esp esr ess ka- kaa kac kae kak kap kar kas kca kcc kce kck kcp kcr kcs ke- kea kec kee kek kep ker kes kkc kke kkk kkp kkr kks kpa kpc kpe kpk kpp kpr kps kra krc krk krp krr krs ksa ksc kse ksk ksp ksr kss p-p paa pac pae pak pap par pas pca pcc pce pck pcp pcr pcs pea pec pee pek pep per pes pka pkc pke pkp pkr pks ppa ppc ppe ppk ppp ppr pps pra prc pre prk prp prr prs ps- psa psc pse psk psp psr pss ra- raa rac rae rak rap rar ras rca rcc rce rcp rcr rcs re- rea rec ree rek rep rer res rkc rke rkk rkp rks rpa rpc rpe rpk rpp rpr rps rra rrc rrk rrp rrr rrs rsa rsc rse rsk rsp rsr rss saa sac sae sak sap sar sas sca scc sce sck scp scr scs se- sea sec see sek sep ser ses sk- ska skc ske skk skp skr sks spa spc spe spk spp spr sps sr- sra src sre srk srp srr srs ss- ssa ssc sse ssk ssp ssr sss