b-u bbb bbk bbo bbt bbu bkb bkk bko bkt bob bok boo bot bou btb btk bto btt btu bub buk buo but buu k-t kbb kbk kbo kbu kkb kkk kkt kku kob kok koo kot kou ktb ktk kto ktt ktu kub kuk kut kuu ob- obb obk obo obt obu okb okk oko oku oo- oob ook ooo oot ot- otb otk oto ott otu ou- ouk ouo out tbb tbk tbo tbt tbu tkb tkk tko tkt to- tob tok too tot tou ttb ttk tto ttt ttu tub tuk tuo tut tuu ubb ubk ubo ubt ubu ukb ukk uku uob uok uoo uot utb utk uto utt utu uut uuu