b-u bbb bbc bbo bbt bbu bcb bcc bco bct bcu bob boc boo bot bou btb btc bto btt btu bub buc buo but buu c-- cbb cbc cbo cbt cbu ccb ccc cco cct ccu co- cob coc coo cot cou ctb ctc cto ctt ctu cub cuc cuo cut cuu ob- obb obc obo obt obu oc- ocb occ oco oct ocu oo- oob ooc ooo oot ot- otb otc oto ott otu ou- ouc ouo out tbb tbc tbo tbt tbu tcb tcc tco tct tcu to- tob toc too tot tou ttb ttc tto ttt ttu tub tuc tuo tut tuu ubb ubc ubo ubt ubu ucb ucc uco uct ucu uob uoc uoo uot utb utc uto utt utu uuc uut uuu