-er c-- ccc cce ccg ccn ccr ccx ce- cec cee ceg cen cer cex cgc cge cgg cgn cgr cn- cnc cne cng cnn cnr cnx crc cre crg crn crr crx cxc cxr cxx ec- ecc ece ecg ecn ecr ecx eec eee eeg een eer eex egc ege egg egn egr egx en- enc ene eng enn enr erc ere erg ern err ex- exc exe exr exx gcc gce gcg gcn gcr ge- gec gee geg gen ger gex ggc ggg ggn ggr gnc gne gnn gnr grc gre grg grn grr grx ncc nce ncg ncn ncr ncx ne- nec nee neg nen ner nex ngc nge ngg ngn nnc nne nng nnn nrc nre nrg nrn nrr nrx nxc rcc rce rcg rcn rcr rcx re- rec ree reg ren rer rex rgc rge rgg rgn rgr rgx rnc rng rnn rnr rrc rrg rrn rrr rxr xcr xcx xee xeg xen xer xex xge xnc xrc xrx xxx