-er eee eef eek eel eer eex ef- efe eff efi efl efr efx eie eif eii eik eil eir eix eke ekf eki ekl ekr ele elf eli elk ell elr elx ere erf eri erk erl err ex- exe exi exl exr exx fee fef fei fek fel fer fex ffe fff ffi ffk ffl ffr ffx fie fif fii fik fil fir fix fkf fki fkk fkl fle flf fli fll flr flx fre frf fri frk frl frr fxe fxi fxr fxx i-f ie- iee ief iei iek iel ier iex ife iff ifi ifl ifr ifx iie iif iii iil iir iix ike ikf iki ikk ikl ikr ikx il- ile ilf ili ilk ill ilr ilx ir- ire irf iri irk irl irr irx ixe ixi ixl ke- kee kef kei kek kel ker kex kff kfi kfx kie kif kii kik kil kir kix kke kki kkk kkl kkr kl- klf kli klr klx krf kri krk krl krr kxl lee lef lei lek lel ler lex lfe lff lfi lfk lfl lfr lfx lie lif lii lik lil lir lix lkl lkr lle llf lli llk lll llr lrf lri lrk lrr lxi lxr lxx re- ree ref rei rek rel rer rex rfe rff rfi rfk rfl rfr rie rif rii rik ril rir rix rke rkf rkk rle rlf rli rll rlr rrf rri rrk rrl rrr rxr xee xel xer xex xfe xfl xfx xie xii xix xke xkl xlf xli xlr xrf xrx xxi xxl xxx