First position of a target in a sorted array

Question

Given a nondecreasing array and a target value, report where the target first appears, or `-1` when it is missing. A logarithmic search is expected, even though the same value may occur many times.

```python
def solve(raw: str) -> str: ...
```

## Requirements

- Line one is the element count `n`. Line two holds the `n` space-separated integers in nondecreasing order, and is empty when `n` is 0. Line three is the target.
- Return the smallest zero-based index holding the target, as a decimal string with no padding.
- Return `-1` when the array is empty or the target never appears.
- Repeated values are expected, so an ordinary equality hit is not enough; after a match keep searching to the left while remembering the best index seen.
- Keep the running time logarithmic in `n`. Negative values, a target below the minimum, and a target above the maximum must all work.
- `run_case` passes `case["stdin"]` to `solve`.
- Do not append a trailing newline to the returned string; return the value exactly once.