a-a a-b aaa aab aae aas aau aax ab- aba abb abe abs abu abx aea aeb aee aes aeu aex as- asa asb ase ass asu asx au- aua aub aue aus aux ax- axa axe axs axx b-u baa bab bae bas bau bax bba bbb bbe bbs bbu bbx be- bea beb bee bes beu bex bsa bsb bse bss bsu bsx bua bub bue bus buu bux bxb bxx eaa eab eae eas eau eax eba ebb ebe ebs ebu ebx eea eeb eee ees eex es- esa esb ese ess esu esx eu- eua eub eue eus eux ex- exa exe exs exu exx saa sab sae sas sau sax sba sbb sbe sbs sbu sbx se- sea seb see ses seu sex ss- ssa ssb sse sss ssu ssx sua sub sue sus suu sux sxs sxu ua- uaa uab uae uas uau uba ubb ube ubs ubu ubx uea ueb uee ues usa usb use uss usu usx uua uue uus uuu uxb uxu xaa xas xau xbe xbx xee xes xeu xex xsa xsb xss xue xus xxx