Proving a sequence converges without finding limit

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Just asking a quick question about converging sequences. We were told to prove the sequence below converges and then find the limit:

$a_{n}=\frac{(-1)^n + \cos(2^n)}{n^2}$

We were told that we can't use the $\epsilon-N$ definiton, so I assume that we have to use the squeeze theorem but I am strugging to see how to use that to prove that the series converges without actually finding the limit.

If someone could just give me a hint where to start I should be able to go from there.