b-u bbb bbg bbo bbr bbu bgb bgg bgo bgr bgu bgv bob bog boo bor bou bov brb brg bro brr bru brv bub bug buo bur buu bvb bvg bvo bvr bvu bvv gbg gbo gbr gbu gbv ggb ggg ggo ggr ggu ggv gob gog goo gor gou gov grb grg gro grr gru grv gu- gub gug guo gur guu guv gvb gvg gvo gvr gvu ob- obb obg obo obr obu obv ogg ogo oo- oob oog ooo oor oov or- orb org oro orr oru orv ou- ouo our ov- ovb ovo ovv rbb rbg rbo rbr rbu rgb rgg rgo rgr rgv rob rog roo ror rou rov rrb rrg rrr rru rub rug ruo rur ruu ruv rvb rvg rvo rvr rvu rvv ubb ubg ubo ubr ubu ubv ugb ugg ugo ugr ugu uob uog uoo uor ur- urb urg uro urr uru uug uur uuu uvb uvo uvu uvv vbg vbo vbr vbv vgg vgo vgr vgu vob vog voo vor vou vov vrb vrg vrr vru vug vur vuv vvb vvg vvo vvr vvv