bbb bbd bbk bbo bbt bdb bdd bdk bdo bdt bkb bkk bko bkt bob bod bok boo bot btb btd btk bto btt dbb dbd dbk dbo dbt ddb ddd ddk ddo ddt dkb dkk dko dkt dob dod dok doo dot dtb dtd dtk dto dtt k-t kbb kbd kbk kbo kdb kdk kdo kdt kkb kkk kkt kob kod kok koo kot ktb ktk kto ktt ob- obb obd obk obo obt odb odd odo odt okb okd okk oko oo- oob ood ook ooo oot ot- otb otd otk oto ott tbb tbd tbk tbo tbt tdb tdd tdk tdo tdt tkb tkk tko tkt to- tob tod tok too tot ttb ttd ttk tto ttt