b-u bbb bbo bbr bbt bbu bbx bob boo bor bot bou box brb bro brr brt bru brx btb bto btr btt btu btx bub buo bur but buu bux bxb bxo bxx ob- obb obo obr obt obu obx oo- oob ooo oor oot oox or- orb oro orr ort oru orx ot- otb oto otr ott otu ou- ouo our out ox- oxb oxo oxt oxx rbb rbo rbr rbt rbu rbx rob roo ror rot rou rox rrb rrr rrt rru rtb rto rtr rtt rtu rtx rub ruo rur rut ruu rux rxr t-x tbb tbo tbr tbt tbu to- tob too tor tot tou tox trb tro trr trt tru trx ttb tto ttr ttt ttu ttx tub tuo tur tut tuu tux txt txu ubb ubo ubr ubt ubu ubx uob uoo uor uot uox ur- urb uro urr urt uru urx utb uto utr utt utu utx uur uut uuu uxb uxo uxr uxt uxu xbr xbx xoo xor xot xox xrt xrx xtr xtx xxo xxx