-er c-- ccc cce cck cco ccr ccu ce- cec cee cek ceo cer ceu ckc cko co- coc coe cok coo cor cou crc cre crk cro crr cru cuc cue cuk cuo cur cuu ec- ecc ece eck eco ecr ecu eec eee eek eeo eer ekc eke eko ekr eku eo- eoc eoe eok eoo eor eou erc ere erk ero err eru eu- euc eue eur kcc kce kck kcr kcu ke- kec kee kek keo ker kkc kke kkk kkr kku koc koe kok koo kor kou krc krk kro krr kru kuc kue kuk kur kuu oc- occ ock oco ocr ocu oec oee oeo oer okc oke okk oko okr oku oo- ooc ook ooo oor or- orc ore ork oro orr oru ou- ouc oue ouk ouo our rcc rce rco rcr rcu re- rec ree rek reo rer reu rkc rke rkk rko rku roc roe rok roo ror rou rrc rrk rrr rru ruc rue ruk ruo rur ruu ucc uce uck uco ucr ucu uec uee uer ukc uke ukk ukr uku uoc uoe uok uoo uor ur- urc ure urk uro urr uru uuc uue uur uuu