-er c-- ccc cce ccr cct ccx ce- cec cee cer cet cex crc cre crr crt crx ctc cte ctr ctt ctx cxc cxr cxt cxx ec- ecc ece ecr ect ecx eec eee eer eet eex erc ere err ert etc ete etr ett etx ex- exc exe exr ext exx rcc rce rcr rct rcx re- rec ree rer ret rex rrc rrr rrt rtc rte rtr rtt rtx rxr t-x tcc tce tcr tct tcx te- tec tee ter tet tex trc tre trr trt trx ttc tte ttr ttt ttx txe txt xcr xcx xee xer xet xex xrc xrt xrx xtc xtr xtx xxx