bbb bbn bbo bbr bbt bnb bnn bno bnr bnt bob bon boo bor bot brb brn bro brr brt btb btn bto btr btt nbb nbn nbo nbr nbt nnb nnn nno nnt no- nob non noo nor not nrb nrn nro nrr nrt ntb ntn nto ntr ntt ob- obb obn obo obr obt on- onb onn ono onr ont oo- oob oon ooo oor oot or- orb orn oro orr ort ot- otb otn oto otr ott rbb rbn rbo rbr rbt rnb rnn rno rnr rnt rob ron roo ror rot rrb rrn rrr rrt rtb rtn rto rtr rtt tbb tbn tbo tbr tbt tnb tnn tno tnr tnt to- tob ton too tor tot trb trn tro trr trt ttb ttn tto ttr ttt