$M$ is a compact space. Assume $f$ is upper semi-continuous on $M$, $g$ is lower semi-continuous on $M$, and $f(x) \geq g(x)$ for any $x\in M$. If $f(x_0) = g(x_0) $ for some point $x_0\in M$, is it true that $f$ is continuous at $x_0$? What about the topology of the set of the continuous points of $f$? (open or closed?) Thank you!