It is desired to implement the Bernstein$$Vazirani algorithm, but $($alas$)$ the only controlled gates

you have available to you are controlled Hadamard gates. Recall the standard B$-$V algorithm,

below.

In general, if an input gate is part of the code, it flips the output $($auxiliary$)$ bit from a $|0>$ to $|1>$

or a $|1>$ to a $|0>-$ where