-er c-- ccc ccd cce ccr ccs ccx cdc cdd cde cdr cds cdx ce- cec ced cee cer ces cex crc crd cre crr crs crx csc csd cse csr css csx cxc cxr cxs cxx dcc dcd dce dcr dcs dcx ddc ddd dde ddr dds ddx de- dec ded dee der des dex drc drd dre drr drs drx dsc dsd dse dsr dss dsx dxc dxd dxr dxs dxx ec- ecc ecd ece ecr ecs ecx ed- edc edd ede edr eds edx eec eed eee eer ees eex erc erd ere err ers es- esc esd ese esr ess esx ex- exc exd exe exr exs exx rcc rcd rce rcr rcs rcx rdc rdd rde rdr rds rdx re- rec red ree rer res rex rrc rrd rrr rrs rsc rsd rse rsr rss rsx rxr rxs scc scd sce scr scs scx sdc sdd sde sdr sds se- sec sed see ser ses sex sr- src srd sre srr srs srx ss- ssc ssd sse ssr sss ssx sxc sxs xcd xcr xcx xdc xde xdr xds xed xee xer xes xex xrc xrd xrx xsc xss xxx