b-u bbb bbc bbk bbr bbu bcb bcc bck bcr bcu bkb bkc bkk bkr brb brk brr bru bub buc buk bur buu c-- cbb cbc cbk cbr cbu ccb ccc cck ccr ccu ckb ckc crb crc crk crr cru cub cuc cuk cur cuu kbb kbc kbk kbr kbu kcb kcc kck kcr kcu kkb kkc kkk kkr kku krc krk krr kru kub kuc kuk kur kuu rbb rbc rbk rbr rbu rcb rcc rcr rcu rkb rkc rkk rku rrb rrc rrk rrr rru rub ruc ruk rur ruu ubb ubc ubk ubr ubu ucb ucc uck ucr ucu ukb ukc ukk ukr uku ur- urb urc urk urr uru uuc uur uuu