-er eee een eep eer eet eex en- ene enn enp enr ent ep- epe epn epp epr ept epx ere ern erp err ert ete etn etp etr ett etx ex- exe exp exr ext exx ne- nee nen nep ner net nex nne nnn nnp nnt npe npn npp npr npt nre nrn nrp nrr nrt nrx nte ntn ntp ntr ntt ntx nxt p-p pee pen pep per pet pex pn- pne pnn pnp pnr pnt pnx ppe ppn ppp ppr ppt ppx pre prn prp prr prt prx pt- pte ptn ptp ptr ptt ptx pxe pxr pxt re- ree ren rep rer ret rex rnn rnp rnr rnt rpe rpn rpp rpr rpt rpx rrn rrp rrr rrt rte rtn rtp rtr rtt rtx rxp rxr t-x te- tee ten tep ter tet tex tne tnn tnp tnr tnt tnx tpe tpn tpp tpr tpt tpx tre trn trp trr trt trx tte ttn ttp ttr ttt ttx txe txn txt xee xen xep xer xet xex xpe xpn xpp xpt xrt xrx xtp xtr xtx xxp xxx