**Inputs:**

  1. A marking oracle implementing an unknown $N$-bit function $f(x)$.
  2. $N$ qubits in an arbitrary state (input/query register).
  
**Goal:**

Flip the phase of each basis state $|x\rangle$ for which $f(x) = 1$. You can only access $f(x)$ via the marking oracle you are given.

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<details>
  <summary><b>Need a hint?</b></summary>
    Recall that you can allocate extra qubits to assist in this operation.  Is there a state that you could prepare with an auxiliary qubit which would help you to convert the marking oracle to a phase oracle?
</details>
