fff ffn ffo ffp ffr ffs fnf fnn fnp fnr fns fof fon foo fop for fos fpn fpo fpp fpr fps frf frn fro frp frr frs fsf fsn fso fsp fsr fss nff nfn nfo nfp nfr nfs nnf nnn nno nnp nns no- nof non noo nop nor nos npf npn npo npp npr nps nrf nrn nro nrp nrr nrs nsf nsn nso nsp nsr nss of- off ofn ofo ofp ofr ofs on- onf onn ono onp onr ons oo- oof oon ooo oop oor oos op- opf opn opo opp opr ops or- orf orn oro orp orr ors os- osf osn oso osp osr oss p-p pff pfn pfo pfp pfr pfs pn- pnf pnn pno pnp pnr pns pof pon poo pop por pos ppf ppn ppo ppp ppr pps prf prn pro prp prr prs ps- psf psn pso psp psr pss rff rfn rfo rfp rfr rfs rnn rno rnp rnr rns rof ron roo rop ror ros rpf rpn rpo rpp rpr rps rrf rrn rrp rrr rrs rsf rsn rso rsp rsr rss sff sfn sfo sfp sfr sfs snf snn sno snp snr sns sof son soo sop sor sos spf spn spo spp spr sps sr- srf srn sro srp srr srs ss- ssf ssn sso ssp ssr sss