# Thinking Inside the Box

Geometry Level 2

$$Q$$ is the point of intersection of the diagonals of one face of a cube whose edges have length $$2\text{ cm}$$.

If the length of $$QR$$ (in $$\text{cm}$$) is $$x\sqrt{y}$$, where $$x$$ and $$y$$ are positive integers with $$y$$ square-free, find $$x+y-xy$$.

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