fff ffi ffs fft ffy fif fii fis fit fsf fsi fss fst ftf fti fts ftt fty fy- fyi i-f iff ifi ifs ift ify iif iii iis iit is- isf isi iss ist isy itf iti its itt ity iys iyt iyy sff sfi sfs sft sif sii sis sit ss- ssf ssi sss sst stf sti sts stt sty sy- syi sys syt tff tfi tfs tft tif tii tis tit tiy tsf tsi tss tst tsy ttf tti tts ttt tty tyf tys tyt yff yfs yft yif yii yis yit ysi yss yst ysy ytf yts ytt yyf yys yyt yyy