-er c-- ccc cce ccf ccn ccr ccx ce- cec cee cef cen cer cex cfc cfe cff cfn cfr cfx cn- cnc cne cnf cnn cnr cnx crc cre crf crn crr crx cxc cxf cxr cxx ec- ecc ece ecf ecn ecr ecx eec eee eef een eer eex ef- efc efe eff efr efx en- enc ene enf enn enr erc ere erf ern err ex- exc exe exr exx fcc fce fcf fcn fcr fcx fec fee fef fen fer fex ffc ffe fff ffn ffr ffx fnc fne fnf fnn fnr fnx frc fre frf frn frr fxe fxr fxx ncc nce ncf ncn ncr ncx ne- nec nee nef nen ner nex nfc nfe nff nfn nfr nnc nne nnf nnn nrc nre nrf nrn nrr nrx nxc rcc rce rcf rcn rcr rcx re- rec ree ref ren rer rex rfc rfe rff rfn rfr rnc rnn rnr rrc rrf rrn rrr rxr xcf xcr xcx xee xen xer xex xfe xfn xfx xnc xrc xrf xrx xxx