eee eem eeo ees eex em- eme emm emo ems emx eo- eoe eom eoo eos es- ese esm eso ess esx ex- exe exo exs exx m-o mee mem meo mes mex mme mmm mmo mms mmx moe mom moo mos mox mse msm mso mss msx mxs oee oem oeo oes oex om- ome omm omo oms omx oo- oom ooo oos oox os- ose osm oso oss osx ox- oxo oxx se- see sem seo ses sex sme smm smo sms smx soe som soo sos sox ss- sse ssm sso sss ssx sxm sxs xee xem xes xex xmm xmo xms xmx xom xoo xos xox xsm xss xxo xxx