A small block for the topic "{topic}" may be a sub-topic of a bigger block. Pick the ONE block it belongs under — or 0 if it stands on its own after all.

SMALL BLOCK:
{small}

CANDIDATE PARENT BLOCKS:
{parents}

Rules:
- Pick the number of the block the small block is a detail/sub-step/property of.
- 0 = it is NOT a sub-topic of any of them (it is actually standalone).
- Only pick a parent if the small block clearly belongs INSIDE it.

Write ONLY the JSON file to: {out_path}

Format (the chosen parent number, or 0):
{{"parent": 0}}