Let $\displaystyle r^2-ms^2 \in \mathbb {Z} $, and suppose that m is a square free integer with r,s not integers, prove that $\displaystyle m \equiv 1 \ (mod \ 4)$

Proof so far.

I have $\displaystyle r^2-ms^2 = n \ \ \ \ \ n \in \mathbb {Z} $
$\displaystyle m = \frac {r^2-n}{s^2} $