In $\triangle PQR$, we have $PQ = QR = 34$ and $PR = 32$.  Point $M$ is the midpoint of $\overline{QR}$.  Find $PM$.The answer is in the form k\sqrt{m}+n,. Please provide the value of k + m + n.

Let's think step by step and output the final answer within \boxed{}.
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