The code below is running on an Arduino board. Pin $3$ is connected to a signal generator that is producing a $23Hz$ square wave at $5V$ amplitude.

Determine how many times the LED connected to pin $13$ will flash on during each $10$ secont interval. For full credit, you must explain how this is determined and show some math.

Note that there is a timer interrupt in this code, a pin interrupt in this code, and some polling code in loop$().$

#include $=0\mathrm{.}033333sec=$