a-a a-b aaa aab aae aau aax ab- aba abb abe abu abx aea aeb aee aeu aex au- aua aub aue aux ax- axa axe axx b-u baa bab bae bau bax bba bbb bbe bbu bbx be- bea beb bee beu bex bua bub bue buu bux bxb bxx eaa eab eae eau eax eba ebb ebe ebu ebx eea eeb eee eex eu- eua eub eue eux ex- exa exe exu exx ua- uaa uab uae uau uba ubb ube ubu ubx uea ueb uee uua uue uuu uxb uxu xaa xau xbe xbx xee xeu xex xue xxx