= Solution
If there is no marked entry, the <Boolean quantum oracle> is the identity. The <uniform superposition state> is a positive eigenstate of the <Grover diffusion operator>:
$$
V|s\rangle=(2|s\rangle\langle s|-I)|s\rangle=|s\rangle.
$$
Thus every iteration leaves the full state $|s\rangle\otimes|-\rangle$ unchanged. The measured search bits have the <uniform distribution>
$$
\boxed{\mathbb P(\text{output }x)=\frac1N\quad(0\leq x<N).}
$$
Only the first $n$ qubits are measured in the printed circuit. If the untouched ancilla were also measured in the computational basis, its bit would be an independent fair bit, giving probability $1/(2N)$ for each joint outcome.
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