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 girl does a handstand on a bed with blue sheets.
Hypothesis: A girl is practicing gymnastics on her bed.
Update: The girl has a headstand video up on YouTube that she is copying
strengthener

Premise: A flying machine with a yellow sail is landing with industrial buildings in the background.
Hypothesis: The machine is not gas-operated.
Update: The machine has a battery.
strengthener

Premise: A group of men are on a stage and playing guitars.
Hypothesis: A group of young men play their rock guitars
Update: The men are dressed in rock band outfits.

strengthener