-er a-a aaa aae aan aap aar aax aea aee aen aep aer aex an- ana ane ann anp anr anx ap- apa ape apn app apr apx ar- ara are arn arp arr arx ax- axa axe axn axp axr axx eaa eae ean eap ear eax eea eee een eep eer eex en- ena ene enn enp enr ep- epa epe epn epp epr epx era ere ern erp err ex- exa exe exp exr exx naa nae nan nap nar nax ne- nea nee nen nep ner nex nna nne nnn nnp npa npe npn npp npr nra nre nrn nrp nrr nrx p-p paa pae pan pap par pax pea pee pen pep per pex pn- pna pne pnn pnp pnr pnx ppa ppe ppn ppp ppr ppx pra pre prn prp prr prx pxe pxr ra- raa rae ran rap rar rax re- rea ree ren rep rer rex rna rnn rnp rnr rpa rpe rpn rpp rpr rpx rra rrn rrp rrr rxp rxr xaa xan xap xar xee xen xep xer xex xna xpa xpe xpn xpp xrx xxp xxx