cccc cccp ccee ccpe ccpp ccpr ccrc ccre ccrp cec- cece cecp ceec cepc cepe cepp cepr cer- cerc cere cerp cexe cpce cpep cper cpre crcc crce crcr cre- crec cree crep crex crpc cxxx eccc ecce ecpp ecrc ecrr eeee eerc epcc epec epee eper eppc eppp eprp epxp er-x ercc erce ercp erec erer erpe errc erre exec exer expr exrx pccc pcce pcep pcer pcpp pcrc pcre pece pecr peec peep peer pepe per- perc pere perp perr ppcc pper pppp pprc prcc prcp pre- prec pree prep prex rccc rcep recc rece recp recr reep repe repp repr rere rexx rrrr xeer xer- xexe xpcc xper xrep xxxx