b-u bbb bbg bbr bbs bbu bgb bgg bgr bgs bgu brb brg brr brs bru bsb bsg bsr bss bsu bub bug bur bus buu gbg gbr gbs gbu ggb ggg ggr ggs ggu grb grg grr grs gru gsb gsg gsr gss gsu gu- gub gug gur gus guu rbb rbg rbr rbs rbu rgb rgg rgr rgs rrb rrg rrr rrs rru rsb rsg rsr rss rsu rub rug rur rus ruu sbb sbg sbr sbs sbu sgb sgg sgr sgs sgu sr- srb srg srr srs ss- ssb ssg ssr sss ssu sub sug sur sus suu ubb ubg ubr ubs ubu ugb ugg ugr ugs ugu ur- urb urg urr urs uru usb usg usr uss usu uug uur uus uuu