-er c-- ccc cce ccm ccr ccx ce- cec cee cem cer cex cmc cme cmm cmr cmx crc cre crm crr crx cxc cxr cxx ec- ecc ece ecm ecr ecx eec eee eem eer eex em- emc eme emm emr emx erc ere erm err ex- exc exe exr exx m-r mc- mcc mce mcm mcr mcx mec mee mem mer mex mmc mme mmm mmr mmx mrc mre mrm mrr mrx mxc mxr rcc rce rcm rcr rcx re- rec ree rem rer rex rmc rme rmm rmr rmx rrc rrm rrr rxr xcr xcx xee xem xer xex xmc xmm xmr xmx xrc xrx xxx