-er c-- ccc cce ccp ccr ccx ce- cec cee cep cer cex cpc cpe cpp cpr cpx crc cre crp crr crx cxc cxp cxr cxx ec- ecc ece ecr ecx eec eee eep eer eex ep- epc epe epp epr epx erc ere erp err ex- exc exe exp exr exx p-p pcc pce pcp pcr pcx pec pee pep per pex ppc ppe ppp ppr ppx prc pre prp prr prx pxc pxe pxr rcc rce rcp rcr rcx re- rec ree rep rer rex rpc rpe rpp rpr rpx rrc rrp rrr rxp rxr xcp xcr xcx xee xep xer xex xpc xpe xpp xrc xrx xxp xxx