-er c-- ccc cce cco ccp ccr cct ccx ce- cec cee ceo cep cer cet cex co- coc coe coo cop cor cot cox cpc cpe cpo cpp cpr cpt cpx crc cre cro crp crr crt crx ctc cte cto ctp ctr ctt ctx cxc cxo cxp cxr cxt cxx ec- ecc ece eco ecr ect ecx eec eee eeo eep eer eet eex eo- eoc eoe eoo eop eor eot ep- epc epe epo epp epr ept epx erc ere ero erp err ert etc ete eto etp etr ett etx ex- exc exe exo exp exr ext exx oc- occ oco ocp ocr oct ocx oec oee oeo oep oer oet oex oo- ooc ooo oop oor oot oox op- opc ope opo opp opr opt opx or- orc ore oro orp orr ort orx ot- otc ote oto otp otr ott ox- oxc oxo oxt oxx p-p pcc pce pco pcp pcr pct pcx pec pee peo pep per pet pex poc poe poo pop por pot pox ppc ppe ppo ppp ppr ppt ppx prc pre pro prp prr prt prx pt- ptc pte pto ptp ptr ptt ptx pxc pxe pxr pxt rcc rce rco rcp rcr rct rcx re- rec ree reo rep rer ret rex roc roe roo rop ror rot rox rpc rpe rpo rpp rpr rpt rpx rrc rrp rrr rrt rtc rte rto rtp rtr rtt rtx rxp rxr t-x tcc tce tco tcp tcr tct tcx te- tec tee teo tep ter tet tex to- toc toe too top tor tot tox tpc tpe tpo tpp tpr tpt tpx trc tre tro trp trr trt trx ttc tte tto ttp ttr ttt ttx txe txt xcp xcr xcx xee xep xer xet xex xoc xoo xop xor xot xox xpc xpe xpo xpp xpt xrc xrt xrx xtc xtp xtr xtx xxo xxp xxx