b-u bbb bbf bbo bbr bbt bbu bbx bfb bff bfo bfr bft bfu bfx bob bof boo bor bot bou box brb brf bro brr brt bru brx btb btf bto btr btt btu btx bub buf buo bur but buu bux bxb bxo bxx fbb fbf fbo fbr fbt fbu fbx fff ffo ffr fft ffu ffx fob fof foo for fot fou fox frb frf fro frr frt fru ftb ftf fto ftr ftt ftu ftx fub fuf fuo fur fut fuu fux fxr fxt fxu fxx ob- obb obf obo obr obt obu obx of- ofb off ofo ofr oft ofu ofx oo- oob oof ooo oor oot oox or- orb orf oro orr ort oru orx ot- otb otf oto otr ott otu ou- ouf ouo our out ox- oxb oxf oxo oxt oxx rbb rbf rbo rbr rbt rbu rbx rfb rff rfo rfr rft rfu rob rof roo ror rot rou rox rrb rrf rrr rrt rru rtb rtf rto rtr rtt rtu rtx rub ruf ruo rur rut ruu rux rxr t-x tbb tbf tbo tbr tbt tbu tfb tff tfo tfr tft tfu tfx to- tob tof too tor tot tou tox trb trf tro trr trt tru trx ttb ttf tto ttr ttt ttu ttx tub tuf tuo tur tut tuu tux txf txt txu ubb ubf ubo ubr ubt ubu ubx uff ufo ufr uft ufu ufx uob uoo uor uot uox ur- urb urf uro urr urt uru urx utb utf uto utr utt utu utx uur uut uuu uxb uxf uxo uxr uxt uxu xbr xbx xft xfx xof xoo xor xot xox xrf xrt xrx xtf xtr xtx xxo xxx