bbb bbe bbk bbo bbt bbx be- beb bee bek beo bet bex bkb bke bkk bko bkt bkx bob boe bok boo bot box btb bte btk bto btt btx bxb bxo bxx ebb ebe ebk ebo ebt ebx eeb eee eek eeo eet eex ekb eke eko ekt eo- eob eoe eok eoo eot etb ete etk eto ett etx ex- exe exo ext exx k-t kbb kbe kbk kbo kbx ke- keb kee kek keo ket kex kkb kke kkk kkt kob koe kok koo kot ktb kte ktk kto ktt kxo ob- obb obe obk obo obt obx oeb oee oeo oet oex okb oke okk oko oo- oob ook ooo oot oox ot- otb ote otk oto ott ox- oxb oxo oxt oxx t-x tbb tbe tbk tbo tbt te- teb tee tek teo tet tex tkb tke tkk tko tkt to- tob toe tok too tot tox ttb tte ttk tto ttt ttx txe txk txt xbe xbx xee xet xex xkb xke xok xoo xot xox xtx xxo xxx