-er c-- ccc cce ccn ccr cct ccx ce- cec cee cen cer cet cex cn- cnc cne cnn cnr cnt cnx crc cre crn crr crt crx ctc cte ctn ctr ctt ctx cxc cxr cxt cxx ec- ecc ece ecn ecr ect ecx eec eee een eer eet eex en- enc ene enn enr ent erc ere ern err ert etc ete etn etr ett etx ex- exc exe exr ext exx ncc nce ncn ncr nct ncx ne- nec nee nen ner net nex nnc nne nnn nnt nrc nre nrn nrr nrt nrx ntc nte ntn ntr ntt ntx nxc nxt rcc rce rcn rcr rct rcx re- rec ree ren rer ret rex rnc rnn rnr rnt rrc rrn rrr rrt rtc rte rtn rtr rtt rtx rxr t-x tcc tce tcn tcr tct tcx te- tec tee ten ter tet tex tnc tne tnn tnr tnt tnx trc tre trn trr trt trx ttc tte ttn ttr ttt ttx txe txn txt xcr xcx xee xen xer xet xex xnc xrc xrt xrx xtc xtr xtx xxx