bbb bbe bbo bbs bbx be- beb bee beo bes bex bob boe boo bos box bsb bse bso bss bsx bxb bxo bxx ebb ebe ebo ebs ebx eeb eee eeo ees eex eo- eob eoe eoo eos es- esb ese eso ess esx ex- exe exo exs exx ob- obb obe obo obs obx oeb oee oeo oes oex oo- oob ooo oos oox os- osb ose oso oss osx ox- oxb oxo oxx sbb sbe sbo sbs sbx se- seb see seo ses sex sob soe soo sos sox ss- ssb sse sso sss ssx sxs xbe xbx xee xes xex xoo xos xox xsb xss xxo xxx