Hi everyone!

I'm trying to proof the following proposition, can anyone help me?

If $A$ is a dedekind domain contained in a field $k$ and $a\in A$, then for
a prime ideal $I$ of $A$, if the localization of $A$ at $I$ gives a place(or a prime) of $k$ with maximal ideal $P$ , we have $v_P (a) = m$, where $m$ is the power of $I$ in the decomposition of $(a)$ as factor of prime ideals of $A$.

Thank you in advance!