-er -ic c-- ccc cce cci ccr ccx ce- cec cee cei cer cex ci- cic cie cii cir cix crc cre cri crr crx cxc cxi cxr cxx ec- ecc ece eci ecr ecx eec eee eer eex eic eie eii eir eix erc ere eri err ex- exc exe exi exr exx icc ice ici icr ie- iec iee iei ier iex iic iie iii iir iix ir- irc ire iri irr irx ixc ixe ixi rcc rce rci rcr rcx re- rec ree rei rer rex ric rie rii rir rix rrc rri rrr rxr xci xcr xcx xee xer xex xic xie xii xix xrc xrx xxi xxx