b-u bbb bbc bbe bbf bbk bbu bcb bcc bce bcf bck bcu be- beb bec bee bef bek beu bfb bfc bfe bff bfu bkb bkc bke bkf bkk bub buc bue buf buk buu c-- cbb cbc cbe cbf cbk cbu ccb ccc cce ccf cck ccu ce- ceb cec cee cef cek ceu cfb cfc cfe cff cfk cfu ckb ckc cub cuc cue cuf cuk cuu ebb ebc ebe ebf ebk ebu ec- ecb ecc ece ecf eck ecu eeb eec eee eef eek ef- efb efc efe eff ekb ekc eke ekf eku eu- eub euc eue euf fbb fbc fbe fbf fbk fbu fcb fcc fce fcf fck fcu feb fec fee fef fek feu ffc ffe fff ffk ffu fkb fkc fkf fkk fub fue fuf fuk fuu kbb kbc kbe kbf kbk kbu kcb kcc kce kck kcu ke- keb kec kee kef kek kfc kff kfu kkb kkc kke kkk kku kub kuc kue kuk kuu ubb ubc ube ubf ubk ubu ucb ucc uce ucf uck ucu ueb uec uee uef ufc ufe uff ufu ukb ukc uke ukf ukk uku uuc uue uuu