-er eee eem eep eer eet eex em- eme emm emp emr emt emx ep- epe epm epp epr ept epx ere erm erp err ert ete etm etp etr ett etx ex- exe exp exr ext exx m-r mee mem mep mer met mex mme mmm mmp mmr mmt mmx mpe mpm mpp mpr mpt mpx mre mrm mrp mrr mrt mrx mte mtm mtp mtr mtt mtx mxp mxr p-p pee pem pep per pet pex pme pmm pmp pmr pmt pmx ppe ppm ppp ppr ppt ppx pre prm prp prr prt prx pt- pte ptm ptp ptr ptt ptx pxe pxm pxr pxt re- ree rem rep rer ret rex rme rmm rmp rmr rmt rmx rpe rpm rpp rpr rpt rpx rrm rrp rrr rrt rte rtm rtp rtr rtt rtx rxp rxr t-x te- tee tem tep ter tet tex tme tmm tmp tmr tmt tmx tpe tpm tpp tpr tpt tpx tre trm trp trr trt trx tte ttm ttp ttr ttt ttx txe txt xee xem xep xer xet xex xmm xmp xmr xmt xmx xpe xpm xpp xpt xrt xrx xtm xtp xtr xtx xxp xxx