-er a-a a-c aaa aac aae aap aar aas ac- aca acc ace acp acr acs aea aec aee aep aer aes ap- apa apc ape app apr aps ar- ara arc are arp arr ars as- asa asc ase asp asr ass c-- caa cac cae cap car cas cca ccc cce ccp ccr ccs ce- cea cec cee cep cer ces cpa cpc cpe cpp cpr cps cra crc cre crp crr crs csa csc cse csp csr css eaa eac eae eap ear eas ec- eca ecc ece ecr ecs eea eec eee eep eer ees ep- epa epc epe epp epr eps era erc ere erp err ers es- esa esc ese esp esr ess p-p paa pac pae pap par pas pca pcc pce pcp pcr pcs pea pec pee pep per pes ppa ppc ppe ppp ppr pps pra prc pre prp prr prs ps- psa psc pse psp psr pss ra- raa rac rae rap rar ras rca rcc rce rcp rcr rcs re- rea rec ree rep rer res rpa rpc rpe rpp rpr rps rra rrc rrp rrr rrs rsa rsc rse rsp rsr rss saa sac sae sap sar sas sca scc sce scp scr scs se- sea sec see sep ser ses spa spc spe spp spr sps sr- sra src sre srp srr srs ss- ssa ssc sse ssp ssr sss