bbb bbe bbi bbs bbx be- beb bee bei bes bex bi- bib bie bii bis bix bsb bse bsi bss bsx bxb bxi bxx ebb ebe ebi ebs ebx eeb eee ees eex eib eie eii eis eix es- esb ese esi ess esx ex- exe exi exs exx ibb ibe ibi ibs ibx ie- iee iei ies iex iib iie iii iis iix is- isb ise isi iss ixe ixi sbb sbe sbi sbs sbx se- seb see sei ses sex sib sie sii sis six ss- ssb sse ssi sss ssx sxi sxs xbe xbx xee xes xex xie xii xis xix xsb xsi xss xxi xxx