nnn nno nnp nns no- non noo nop nor nos npn npo npp npr nps nrn nro nrp nrr nrs nsn nso nsp nsr nss on- onn ono onp onr ons oo- oon ooo oop oor oos op- opn opo opp opr ops or- orn oro orp orr ors os- osn oso osp osr oss p-p pn- pnn pno pnp pnr pns pon poo pop por pos ppn ppo ppp ppr pps prn pro prp prr prs ps- psn pso psp psr pss rnn rno rnp rnr rns ron roo rop ror ros rpn rpo rpp rpr rps rrn rrp rrr rrs rsn rso rsp rsr rss snn sno snp snr sns son soo sop sor sos spn spo spp spr sps sr- srn sro srp srr srs ss- ssn sso ssp ssr sss