Power and size of a min-based test for a uniform location parameter

Let $X_1,X_2,\dots,X_n$ be a random sample from uniform $(\theta-\tfrac12,\theta+\tfrac12)$ distribution. Consider testing $H_0:\theta=-\tfrac12$ vs $H_1:\theta=\tfrac12$. Let $X_{(1)}=\min\{X_1,\dots,X_n\}$. Consider the test: reject $H_0$ if $X_{(1)}>0$ and accept otherwise. Then the power $(p)$ and size $(s)$ of the test $(p,s)$ are given by: