The Beetle on the Meter Stick

A beetle sits at the $17$ cm mark of a meter stick whose marks run from $0$ to $100$. Once per second it steps $1$ cm left or $1$ cm right, each with probability $\frac{1}{2}$, independently of all previous steps. The instant it reaches the $0$ mark or the $100$ mark it walks off the end and is done. What is the expected number of seconds until the beetle leaves the stick?