-er c-- ccc cce cco ccp ccr ce- cec cee ceo cep cer co- coc coe coo cop cor cpc cpe cpo cpp cpr crc cre cro crp crr ec- ecc ece eco ecr eec eee eeo eep eer eo- eoc eoe eoo eop eor ep- epc epe epo epp epr erc ere ero erp err oc- occ oco ocp ocr oec oee oeo oep oer oo- ooc ooo oop oor op- opc ope opo opp opr or- orc ore oro orp orr p-p pcc pce pco pcp pcr pec pee peo pep per poc poe poo pop por ppc ppe ppo ppp ppr prc pre pro prp prr rcc rce rco rcp rcr re- rec ree reo rep rer roc roe roo rop ror rpc rpe rpo rpp rpr rrc rrp rrr