-er c-- ccc cce cco ccr ccs ce- cec cee ceo cer ces co- coc coe coo cor cos crc cre cro crr crs csc cse cso csr css ec- ecc ece eco ecr ecs eec eee eeo eer ees eo- eoc eoe eoo eor eos erc ere ero err ers es- esc ese eso esr ess oc- occ oco ocr ocs oec oee oeo oer oes oo- ooc ooo oor oos or- orc ore oro orr ors os- osc ose oso osr oss rcc rce rco rcr rcs re- rec ree reo rer res roc roe roo ror ros rrc rrr rrs rsc rse rso rsr rss scc sce sco scr scs se- sec see seo ser ses soc soe soo sor sos sr- src sre sro srr srs ss- ssc sse sso ssr sss