eee een eep ees eex en- ene enn enp ens ep- epe epn epp eps epx es- ese esn esp ess esx ex- exe exp exs exx ne- nee nen nep nes nex nne nnn nnp nns npe npn npp nps nse nsn nsp nss nsx p-p pee pen pep pes pex pn- pne pnn pnp pns pnx ppe ppn ppp pps ppx ps- pse psn psp pss psx pxe pxs se- see sen sep ses sex sne snn snp sns spe spn spp sps spx ss- sse ssn ssp sss ssx sxn sxs xee xen xep xes xex xns xpe xpn xpp xps xsp xss xxp xxx