bbb bbe bbf bbi bbk bbx be- beb bee bef bei bek bex bfb bfe bff bfi bfx bi- bib bie bif bii bik bix bkb bke bkf bkk bkx bxb bxi bxx ebb ebe ebf ebi ebk ebx eeb eee eef eek eex ef- efb efe eff efi efx eib eie eif eii eik eix ekb eke ekf eki ex- exe exi exx fbb fbe fbf fbi fbk fbx feb fee fef fei fek fex ffe fff ffi ffk ffx fib fie fif fii fik fix fkb fkf fki fkk fxe fxi fxx i-f ibb ibe ibf ibi ibk ibx ie- iee ief iei iek iex ifb ife iff ifi ifx iib iie iif iii iix ikb ike ikf iki ikk ikx ixe ixi kbb kbe kbf kbi kbk kbx ke- keb kee kef kei kek kex kff kfi kfx kib kie kif kii kik kix kkb kke kki kkk xbe xbx xee xex xfe xfx xie xii xix xkb xke xxi xxx