-er c-- ccc cce cco ccp ccr ccs ce- cec cee ceo cep cer ces co- coc coe coo cop cor cos cpc cpe cpo cpp cpr cps crc cre cro crp crr crs csc cse cso csp csr css ec- ecc ece eco ecr ecs eec eee eeo eep eer ees eo- eoc eoe eoo eop eor eos ep- epc epe epo epp epr eps erc ere ero erp err ers es- esc ese eso esp esr ess oc- occ oco ocp ocr ocs oec oee oeo oep oer oes oo- ooc ooo oop oor oos op- opc ope opo opp opr ops or- orc ore oro orp orr ors os- osc ose oso osp osr oss p-p pcc pce pco pcp pcr pcs pec pee peo pep per pes poc poe poo pop por pos ppc ppe ppo ppp ppr pps prc pre pro prp prr prs ps- psc pse pso psp psr pss rcc rce rco rcp rcr rcs re- rec ree reo rep rer res roc roe roo rop ror ros rpc rpe rpo rpp rpr rps rrc rrp rrr rrs rsc rse rso rsp rsr rss scc sce sco scp scr scs se- sec see seo sep ser ses soc soe soo sop sor sos spc spe spo spp spr sps sr- src sre sro srp srr srs ss- ssc sse sso ssp ssr sss