-er bbb bbe bbf bbi bbr bbx be- beb bee bef bei ber bex bfb bfe bff bfi bfr bfx bi- bib bie bif bii bir bix brb bre brf bri brr brx bxb bxi bxx ebb ebe ebf ebi ebr ebx eeb eee eef eer eex ef- efb efe eff efi efr efx eib eie eif eii eir eix erb ere erf eri err ex- exe exi exr exx fbb fbe fbf fbi fbr fbx feb fee fef fei fer fex ffe fff ffi ffr ffx fib fie fif fii fir fix frb fre frf fri frr fxe fxi fxr fxx i-f ibb ibe ibf ibi ibr ibx ie- iee ief iei ier iex ifb ife iff ifi ifr ifx iib iie iif iii iir iix ir- irb ire irf iri irr irx ixe ixi rbb rbe rbf rbi rbr rbx re- reb ree ref rei rer rex rfb rfe rff rfi rfr rib rie rif rii rir rix rrb rrf rri rrr rxr xbe xbr xbx xee xer xex xfe xfx xie xii xix xrf xrx xxi xxx