b-u bbb bbn bbr bbt bbu bnb bnn bnr bnt bnu brb brn brr brt bru btb btn btr btt btu bub bun bur but buu nbb nbn nbr nbt nbu nnb nnn nnt nnu nrb nrn nrr nrt nru ntb ntn ntr ntt ntu nub nun nur nut nuu rbb rbn rbr rbt rbu rnb rnn rnr rnt rnu rrb rrn rrr rrt rru rtb rtn rtr rtt rtu rub run rur rut ruu tbb tbn tbr tbt tbu tnb tnn tnr tnt trb trn trr trt tru ttb ttn ttr ttt ttu tub tun tur tut tuu ubb ubn ubr ubt ubu un- unb unn unr unt unu ur- urb urn urr urt uru utb utn utr utt utu uun uur uut uuu