-er c-- ccc cce cco ccr ccu ccx ce- cec cee ceo cer ceu cex co- coc coe coo cor cou cox crc cre cro crr cru crx cuc cue cuo cur cuu cxc cxo cxr cxx ec- ecc ece eco ecr ecu ecx eec eee eeo eer eex eo- eoc eoe eoo eor eou erc ere ero err eru eu- euc eue eur eux ex- exc exe exo exr exu exx oc- occ oco ocr ocu ocx oec oee oeo oer oex oo- ooc ooo oor oox or- orc ore oro orr oru orx ou- ouc oue ouo our ox- oxc oxo oxx rcc rce rco rcr rcu rcx re- rec ree reo rer reu rex roc roe roo ror rou rox rrc rrr rru ruc rue ruo rur ruu rux rxr ucc uce uco ucr ucu uec uee uer uoc uoe uoo uor uox ur- urc ure uro urr uru urx uuc uue uur uuu uxc uxo uxr uxu xcr xcx xee xer xeu xex xoc xoo xor xox xrc xrx xue xxo xxx