In this task, you are given a premise, a hypothesis, and an update. The premise sentence describes a real-world situation and is always assumed to be true. The hypothesis sentence describes an assumption or inference that you might make about that situation having read the premise. The update provides additional information about the situation that might weaken or strengthen the hypothesis. A weakener is a statement that weakens the hypothesis, that is, it makes you much less likely to believe the hypothesis is true. A strengthener is a statement that strengthens the hypothesis, that is, it makes you much more likely to believe the hypothesis is true. Your task is to answer with 'strengthener' or 'weakener' if the update strengthens or weakens the hypothesis, respectively.

Premise: A young african boy skipping rocks.
Hypothesis: There is a rock currently skipping down a pond.
Update: There are several expanding sets of rings on the surface of the pool.
strengthener

Premise: Many people are walking or standing on a busy city sidewalk.
Hypothesis: An angry mob discussing how to storm a building.
Update: They are outside a business that was running a scam and want their money back.
strengthener

Premise: A man throws a small child up in the air.
Hypothesis: A father is playing with his daughter.
Update: The child's mother is looking at them and laughing.

strengthener