fff ffi ffn ffo ffp ffs fif fii fin fip fis fnf fni fnn fnp fns fof foi fon foo fop fos fpi fpn fpo fpp fps fsf fsi fsn fso fsp fss i-f iff ifi ifn ifo ifp ifs iif iii iin iio iip iis in- inf ini inn ino inp ins io- iof ioi ion ioo iop ios ipf ipi ipn ipo ipp ips is- isf isi isn iso isp iss n-i nff nfi nfn nfo nfp nfs nif nii nin nio nip nis nnf nni nnn nno nnp nns no- nof noi non noo nop nos npf npi npn npo npp nps nsf nsi nsn nso nsp nss o-i of- off ofi ofn ofo ofp ofs oif oii oin oio oip ois on- onf oni onn ono onp ons oo- oof ooi oon ooo oop oos op- opf opi opn opo opp ops os- osf osi osn oso osp oss p-p pff pfi pfn pfo pfp pfs pif pii pin pio pip pis pn- pnf pni pnn pno pnp pns pof poi pon poo pop pos ppf ppi ppn ppo ppp pps ps- psf psi psn pso psp pss sff sfi sfn sfo sfp sfs sif sii sin sio sip sis snf sni snn sno snp sns sof soi son soo sop sos spf spi spn spo spp sps ss- ssf ssi ssn sso ssp sss