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 man is performing acrobatics over a group of people kneeling on the ground.
Hypothesis: The acrobat is doing a hard trick.
Update: The acrobat is concentrating very intently.
strengthener

Premise: A young girl is holding an end of the string of a yo-yo in one hand and the body of the pink yo-yo in the other.
Hypothesis: A girl is holding a yo-yo for her friend.
Update: The girl does tricks with the yo-yo.
weakener

Premise: A football player holding a ball is being chased by the Knights team.
Hypothesis: A football player is making a goal while the other team chases him.
Update: The Knights team is far behind the player.

strengthener