fff ffi ffn ffo ffs fft fif fii fin fis fit fnf fni fnn fns fnt fof foi fon foo fos fot fsf fsi fsn fso fss fst ftf fti ftn fto fts ftt i-f iff ifi ifn ifo ifs ift iif iii iin iio iis iit in- inf ini inn ino ins int io- iof ioi ion ioo ios iot is- isf isi isn iso iss ist itf iti itn ito its itt n-i nff nfi nfn nfo nfs nft nif nii nin nio nis nit nnf nni nnn nno nns nnt no- nof noi non noo nos not nsf nsi nsn nso nss nst ntf nti ntn nto nts ntt o-i of- off ofi ofn ofo ofs oft oif oii oin oio ois oit on- onf oni onn ono ons ont oo- oof ooi oon ooo oos oot os- osf osi osn oso oss ost ot- otf oti otn oto ots ott sff sfi sfn sfo sfs sft sif sii sin sio sis sit snf sni snn sno sns snt sof soi son soo sos sot ss- ssf ssi ssn sso sss sst stf sti stn sto sts stt tff tfi tfn tfo tfs tft tif tii tin tio tis tit tnf tni tnn tno tns tnt to- tof toi ton too tos tot tsf tsi tsn tso tss tst ttf tti ttn tto tts ttt