bbb bbe bbk bbo bbt be- beb bee bek beo bet bkb bke bkk bko bkt bob boe bok boo bot btb bte btk bto btt ebb ebe ebk ebo ebt eeb eee eek eeo eet ekb eke eko ekt eo- eob eoe eok eoo eot etb ete etk eto ett k-t kbb kbe kbk kbo ke- keb kee kek keo ket kkb kke kkk kkt kob koe kok koo kot ktb kte ktk kto ktt ob- obb obe obk obo obt oeb oee oeo oet okb oke okk oko oo- oob ook ooo oot ot- otb ote otk oto ott tbb tbe tbk tbo tbt te- teb tee tek teo tet tkb tke tkk tko tkt to- tob toe tok too tot ttb tte ttk tto ttt