-er c-- ccc cce ccp ccr ccs ccx ce- cec cee cep cer ces cex cpc cpe cpp cpr cps cpx crc cre crp crr crs crx csc cse csp csr css csx cxc cxp cxr cxs cxx ec- ecc ece ecr ecs ecx eec eee eep eer ees eex ep- epc epe epp epr eps epx erc ere erp err ers es- esc ese esp esr ess esx ex- exc exe exp exr exs exx p-p pcc pce pcp pcr pcs pcx pec pee pep per pes pex ppc ppe ppp ppr pps ppx prc pre prp prr prs prx ps- psc pse psp psr pss psx pxc pxe pxr pxs rcc rce rcp rcr rcs rcx re- rec ree rep rer res rex rpc rpe rpp rpr rps rpx rrc rrp rrr rrs rsc rse rsp rsr rss rsx rxp rxr rxs scc sce scp scr scs scx se- sec see sep ser ses sex spc spe spp spr sps spx sr- src sre srp srr srs srx ss- ssc sse ssp ssr sss ssx sxc sxs xcp xcr xcx xee xep xer xes xex xpc xpe xpp xps xrc xrx xsc xsp xss xxp xxx