-er c-- ccc cce ccm cco ccr ccx ce- cec cee cem ceo cer cex cmc cme cmm cmo cmr cmx co- coc coe com coo cor cox crc cre crm cro crr crx cxc cxo cxr cxx ec- ecc ece ecm eco ecr ecx eec eee eem eeo eer eex em- emc eme emm emo emr emx eo- eoc eoe eom eoo eor erc ere erm ero err ex- exc exe exo exr exx m-o m-r mc- mcc mce mcm mco mcr mcx mec mee mem meo mer mex mmc mme mmm mmo mmr mmx moc moe mom moo mor mox mrc mre mrm mro mrr mrx mxc mxr oc- occ ocm oco ocr ocx oec oee oem oeo oer oex om- omc ome omm omo omr omx oo- ooc oom ooo oor oox or- orc ore orm oro orr orx ox- oxc oxo oxx rcc rce rcm rco rcr rcx re- rec ree rem reo rer rex rmc rme rmm rmo rmr rmx roc roe rom roo ror rox rrc rrm rrr rxr xcr xcx xee xem xer xex xmc xmm xmo xmr xmx xoc xom xoo xor xox xrc xrx xxo xxx