b-u bbb bbf bbi bbk bbu bfb bff bfi bfu bi- bib bif bii bik biu bkb bkf bkk bub buf bui buk buu fbb fbf fbi fbk fbu fff ffi ffk ffu fib fif fii fik fiu fkb fkf fki fkk fub fuf fui fuk fuu i-f ibb ibf ibi ibk ibu ifb iff ifi ifu iib iif iii iiu ikb ikf iki ikk iku iu- iub iui kbb kbf kbi kbk kbu kff kfi kfu kib kif kii kik kiu kkb kki kkk kku kub kui kuk kuu ubb ubf ubi ubk ubu uff ufi ufu uib uif uii uiu ukb ukf uki ukk uku uuu