fff ffn ffo ffp ffr fnf fnn fnp fnr fof fon foo fop for fpn fpo fpp fpr frf frn fro frp frr nff nfn nfo nfp nfr nnf nnn nno nnp no- nof non noo nop nor npf npn npo npp npr nrf nrn nro nrp nrr of- off ofn ofo ofp ofr on- onf onn ono onp onr oo- oof oon ooo oop oor op- opf opn opo opp opr or- orf orn oro orp orr p-p pff pfn pfo pfp pfr pn- pnf pnn pno pnp pnr pof pon poo pop por ppf ppn ppo ppp ppr prf prn pro prp prr rff rfn rfo rfp rfr rnn rno rnp rnr rof ron roo rop ror rpf rpn rpo rpp rpr rrf rrn rrp rrr