fff ffi ffk ffl ffs ffx fif fii fik fil fis fix fkf fki fkk fkl flf fli fll fls flx fsf fsi fsk fsl fss fsx fxi fxs fxx i-f iff ifi ifl ifs ifx iif iii iil iis iix ikf iki ikk ikl iks ikx il- ilf ili ilk ill ils ilx is- isf isi isk isl iss ixi ixl kff kfi kfs kfx kif kii kik kil kis kix kki kkk kkl kks kl- klf kli kls klx ksf ksi ksk ksl kss kxl lff lfi lfk lfl lfs lfx lif lii lik lil lis lix lkl lks llf lli llk lll lls lsf lsi lsk lsl lss lxi lxx sff sfi sfk sfl sfs sfx sif sii sik sil sis six sk- skf ski skk skl sks skx slf sli slk sll sls slx ss- ssf ssi ssk ssl sss ssx sxi sxl sxs xfl xfs xfx xii xis xix xkl xks xlf xli xls xsi xsl xss xxi xxl xxx