a-a a-b aaa aab aad aae aan aax ab- aba abb abd abe abn abx ad- ada adb add ade adn adx aea aeb aed aee aen aex an- ana anb and ane ann anx ax- axa axe axn axx baa bab bad bae ban bax bba bbb bbd bbe bbn bbx bda bdb bdd bde bdx be- bea beb bed bee ben bex bna bnb bnd bne bnn bnx bxb bxd bxn bxx daa dab dad dae dan dax dba dbb dbd dbe dbn dbx dda ddb ddd dde ddn ddx de- dea deb ded dee den dex dna dnb dnd dne dnn dxd dxn dxx eaa eab ead eae ean eax eba ebb ebd ebe ebn ebx ed- eda edb edd ede edn edx eea eeb eed eee een eex en- ena enb end ene enn ex- exa exd exe exx naa nab nad nae nan nax nba nbb nbd nbe nbn nbx nda ndb ndd nde ndn ne- nea neb ned nee nen nex nna nnb nne nnn nxd xaa xad xan xbe xbx xda xdb xde xed xee xen xex xna xxx