-er eee eem eeo eer eet eex em- eme emm emo emr emt emx eo- eoe eom eoo eor eot ere erm ero err ert ete etm eto etr ett etx ex- exe exo exr ext exx m-o m-r mee mem meo mer met mex mme mmm mmo mmr mmt mmx moe mom moo mor mot mox mre mrm mro mrr mrt mrx mte mtm mto mtr mtt mtx mxr oee oem oeo oer oet oex om- ome omm omo omr omt omx oo- oom ooo oor oot oox or- ore orm oro orr ort orx ot- ote otm oto otr ott ox- oxo oxt oxx re- ree rem reo rer ret rex rme rmm rmo rmr rmt rmx roe rom roo ror rot rox rrm rrr rrt rte rtm rto rtr rtt rtx rxr t-x te- tee tem teo ter tet tex tme tmm tmo tmr tmt tmx to- toe tom too tor tot tox tre trm tro trr trt trx tte ttm tto ttr ttt ttx txe txt xee xem xer xet xex xmm xmo xmr xmt xmx xom xoo xor xot xox xrt xrx xtm xtr xtx xxo xxx