-er c-- ccc ccd cce ccr ccs cdc cdd cde cdr cds ce- cec ced cee cer ces crc crd cre crr crs csc csd cse csr css dcc dcd dce dcr dcs ddc ddd dde ddr dds de- dec ded dee der des drc drd dre drr drs dsc dsd dse dsr dss ec- ecc ecd ece ecr ecs ed- edc edd ede edr eds eec eed eee eer ees erc erd ere err ers es- esc esd ese esr ess rcc rcd rce rcr rcs rdc rdd rde rdr rds re- rec red ree rer res rrc rrd rrr rrs rsc rsd rse rsr rss scc scd sce scr scs sdc sdd sde sdr sds se- sec sed see ser ses sr- src srd sre srr srs ss- ssc ssd sse ssr sss