fff ffi ffp ffs ffy fif fii fip fis fpi fpp fps fpy fsf fsi fsp fss fy- fyi fyp i-f iff ifi ifp ifs ify iif iii iip iis ipf ipi ipp ips ipy is- isf isi isp iss isy iys iyy p-p pff pfi pfp pfs pfy pif pii pip pis ppf ppi ppp pps ps- psf psi psp pss psy py- pyf pys sff sfi sfp sfs sif sii sip sis spf spi spp sps spy ss- ssf ssi ssp sss sy- syi syp sys yff yfs yif yii yip yis ypf yps ysi ysp yss ysy yyf yys yyy