bbb bbn bbo bbr bbs bnb bnn bno bnr bns bob bon boo bor bos brb brn bro brr brs bsb bsn bso bsr bss nbb nbn nbo nbr nbs nnb nnn nno nns no- nob non noo nor nos nrb nrn nro nrr nrs nsb nsn nso nsr nss ob- obb obn obo obr obs on- onb onn ono onr ons oo- oob oon ooo oor oos or- orb orn oro orr ors os- osb osn oso osr oss rbb rbn rbo rbr rbs rnb rnn rno rnr rns rob ron roo ror ros rrb rrn rrr rrs rsb rsn rso rsr rss sbb sbn sbo sbr sbs snb snn sno snr sns sob son soo sor sos sr- srb srn sro srr srs ss- ssb ssn sso ssr sss