fff ffn ffo ffp ffs fft fnf fnn fnp fns fnt fof fon foo fop fos fot fpn fpo fpp fps fpt fsf fsn fso fsp fss fst ftf ftn fto ftp fts ftt nff nfn nfo nfp nfs nft nnf nnn nno nnp nns nnt no- nof non noo nop nos not npf npn npo npp nps npt nsf nsn nso nsp nss nst ntf ntn nto ntp nts ntt of- off ofn ofo ofp ofs oft on- onf onn ono onp ons ont oo- oof oon ooo oop oos oot op- opf opn opo opp ops opt os- osf osn oso osp oss ost ot- otf otn oto otp ots ott p-p pff pfn pfo pfp pfs pft pn- pnf pnn pno pnp pns pnt pof pon poo pop pos pot ppf ppn ppo ppp pps ppt ps- psf psn pso psp pss pst pt- ptf ptn pto ptp pts ptt sff sfn sfo sfp sfs sft snf snn sno snp sns snt sof son soo sop sos sot spf spn spo spp sps spt ss- ssf ssn sso ssp sss sst stf stn sto stp sts stt tff tfn tfo tfp tfs tft tnf tnn tno tnp tns tnt to- tof ton too top tos tot tpf tpn tpo tpp tps tpt tsf tsn tso tsp tss tst ttf ttn tto ttp tts ttt