Analytic, non- constant complex function has finitely many zeros inside the disk $D(0, R)$ for all $R > 0$

Question

I'm learning about complex analysis and need help with the following problem:

Let $f: \mathbb{C} \to \mathbb{C}$ be analytic and non-constant. Show that for every $R > 0$, the complex function $f$ has finitely many zeros inside the disk $D(0, R)$.

I though I could prove the above statement by arguing by contradiction, that is supposing there is an infinite sequence of distinct points $z_k \in D$ with $f(z_k) = 0$ but I didn't get far.

Answer 1

The idea of the proof is this one :

As $D(0,R)$ is compact, your sequence $(z_k)$ has a subsequence that converge to some $z \in D(0,R)$. By continuity of $f$, $f(z) = 0$. But then, this zero is not isolated, so $f \equiv 0$