fff ffi ffo ffp ffs fft fif fii fip fis fit fof foi foo fop fos fot fpi fpo fpp fps fpt fsf fsi fso fsp fss fst ftf fti fto ftp fts ftt i-f iff ifi ifo ifp ifs ift iif iii iio iip iis iit io- iof ioi ioo iop ios iot ipf ipi ipo ipp ips ipt is- isf isi iso isp iss ist itf iti ito itp its itt o-i of- off ofi ofo ofp ofs oft oif oii oio oip ois oit oo- oof ooi ooo oop oos oot op- opf opi opo opp ops opt os- osf osi oso osp oss ost ot- otf oti oto otp ots ott p-p pff pfi pfo pfp pfs pft pif pii pio pip pis pit pof poi poo pop pos pot ppf ppi ppo ppp pps ppt ps- psf psi pso psp pss pst pt- ptf pti pto ptp pts ptt sff sfi sfo sfp sfs sft sif sii sio sip sis sit sof soi soo sop sos sot spf spi spo spp sps spt ss- ssf ssi sso ssp sss sst stf sti sto stp sts stt tff tfi tfo tfp tfs tft tif tii tio tip tis tit to- tof toi too top tos tot tpf tpi tpo tpp tps tpt tsf tsi tso tsp tss tst ttf tti tto ttp tts ttt