-er c-- ccc ccd cce cco ccr cdc cdd cde cdo cdr ce- cec ced cee ceo cer co- coc cod coe coo cor crc crd cre cro crr dcc dcd dce dco dcr ddc ddd dde ddo ddr de- dec ded dee deo der doc dod doe doo dor drc drd dre dro drr ec- ecc ecd ece eco ecr ed- edc edd ede edo edr eec eed eee eeo eer eo- eoc eod eoe eoo eor erc erd ere ero err oc- occ ocd oco ocr odc odd ode odo odr oec oed oee oeo oer oo- ooc ood ooo oor or- orc ord ore oro orr rcc rcd rce rco rcr rdc rdd rde rdo rdr re- rec red ree reo rer roc rod roe roo ror rrc rrd rrr