b-u bbb bbo bbs bbu bbx bby bob boo bos bou box boy bsb bso bss bsu bsx bsy bub buo bus buu bux buy bxb bxo bxx by- byo bys byu ob- obb obo obs obu obx oby oo- oob ooo oos oox os- osb oso oss osu osx ou- ouo ous ox- oxb oxo oxx oxy oyo oys sbb sbo sbs sbu sbx sby sob soo sos sou sox soy ss- ssb sso sss ssu ssx sub suo sus suu sux suy sxs sxu sy- syb sys syu syx ubb ubo ubs ubu ubx uby uob uoo uos uox usb uso uss usu usx uus uuu uxb uxo uxu uyo uys uyu xbx xoo xos xox xsb xss xus xxo xxx xxy xyy ybs yby yob yoo yos you yox yoy ysb yso yss ysu ysy yuo yus yuu yux yuy yxy yyb yys yyu yyy