Degree of an holomorphic map

Question

We have $f(z)=\frac {z^{3}}{1-z^{2}} $ I have found that $0$ is a zero of order $3$, $-1$ and $+1$ simple poles and order $-1$, and $\infty$ isn't a ramification point, but I have no clue how to show that the degree of f is $3$, does someone have an idea? thanks in advance!