fff ffi ffn ffo ffs fif fii fin fis fnf fni fnn fns fof foi fon foo fos fsf fsi fsn fso fss i-f iff ifi ifn ifo ifs iif iii iin iio iis in- inf ini inn ino ins io- iof ioi ion ioo ios is- isf isi isn iso iss n-i nff nfi nfn nfo nfs nif nii nin nio nis nnf nni nnn nno nns no- nof noi non noo nos nsf nsi nsn nso nss o-i of- off ofi ofn ofo ofs oif oii oin oio ois on- onf oni onn ono ons oo- oof ooi oon ooo oos os- osf osi osn oso oss sff sfi sfn sfo sfs sif sii sin sio sis snf sni snn sno sns sof soi son soo sos ss- ssf ssi ssn sso sss