bbb bbk bbo bbr bbt bkb bkk bko bkr bkt bob bok boo bor bot brb brk bro brr brt btb btk bto btr btt k-t kbb kbk kbo kbr kkb kkk kkr kkt kob kok koo kor kot krk kro krr krt ktb ktk kto ktr ktt ob- obb obk obo obr obt okb okk oko okr oo- oob ook ooo oor oot or- orb ork oro orr ort ot- otb otk oto otr ott rbb rbk rbo rbr rbt rkb rkk rko rkt rob rok roo ror rot rrb rrk rrr rrt rtb rtk rto rtr rtt tbb tbk tbo tbr tbt tkb tkk tko tkr tkt to- tob tok too tor tot trb trk tro trr trt ttb ttk tto ttr ttt