-er a-a a-c aaa aac aae aaf aak aap aar aas ac- aca acc ace acf ack acp acr acs aea aec aee aef aek aep aer aes af- afa afc afe aff afk afp afr afs aka akc ake akk akp akr aks ap- apa apc ape apf apk app apr aps ar- ara arc are arf ark arp arr ars as- asa asc ase asf ask asp asr ass c-- caa cac cae caf cak cap car cas cca ccc cce ccf cck ccp ccr ccs ce- cea cec cee cef cek cep cer ces cfa cfc cfe cff cfk cfp cfr cfs cka ckc cks cpa cpc cpe cpf cpk cpp cpr cps cra crc cre crf crk crp crr crs csa csc cse csf csk csp csr css eaa eac eae eaf eak eap ear eas ec- eca ecc ece ecf eck ecr ecs eea eec eee eef eek eep eer ees ef- efa efc efe eff efp efr efs eka ekc eke ekf ekp ekr eks ep- epa epc epe epf epp epr eps era erc ere erf erk erp err ers es- esa esc ese esf esk esp esr ess faa fac fae faf fak fap far fas fca fcc fce fcf fck fcp fcr fcs fea fec fee fef fek fep fer fes ffa ffc ffe fff ffk ffp ffr ffs fka fkc fkf fkk fkp fpa fpc fpe fpk fpp fpr fps fra frc fre frf frk frp frr frs fsa fsc fse fsf fsk fsp fsr fss ka- kaa kac kae kaf kak kap kar kas kca kcc kce kck kcp kcr kcs ke- kea kec kee kef kek kep ker kes kfa kfc kff kfs kkc kke kkk kkp kkr kks kpa kpc kpe kpf kpk kpp kpr kps kra krc krf krk krp krr krs ksa ksc kse ksf ksk ksp ksr kss p-p paa pac pae paf pak pap par pas pca pcc pce pcf pck pcp pcr pcs pea pec pee pef pek pep per pes pfa pfc pfe pff pfk pfp pfr pfs pka pkc pke pkf pkp pkr pks ppa ppc ppe ppf ppk ppp ppr pps pra prc pre prf prk prp prr prs ps- psa psc pse psf psk psp psr pss ra- raa rac rae raf rak rap rar ras rca rcc rce rcf rcp rcr rcs re- rea rec ree ref rek rep rer res rfa rfc rfe rff rfk rfp rfr rfs rkc rke rkf rkk rkp rks rpa rpc rpe rpf rpk rpp rpr rps rra rrc rrf rrk rrp rrr rrs rsa rsc rse rsf rsk rsp rsr rss saa sac sae saf sak sap sar sas sca scc sce scf sck scp scr scs se- sea sec see sef sek sep ser ses sfa sfc sfe sff sfk sfp sfr sfs sk- ska skc ske skf skk skp skr sks spa spc spe spf spk spp spr sps sr- sra src sre srf srk srp srr srs ss- ssa ssc sse ssf ssk ssp ssr sss