What is the genus of compact Riemann surface: $$\Sigma =\{[X,Y,Z]\in \mathbb{C}P^2: Z^2=XY\}.$$
I try to use the Riemann-Herwitz Formula $f: \Sigma \rightarrow \mathbb{S},$ we have $$2g(\Sigma)-2=B_{p}(f)-2\deg(f),$$ where $g(\cdot)$ means the genus and $B_{p}(f)$ is the branch number of $f$ at point $p$.
I know how to calculate the genus of $\Sigma=\{[X,Y,Z]\in \mathbb{C}P^2: X+Y+Z=0\}$, but how to get the genus of a nonlinear polynomial $\Sigma =\{[X,Y,Z]\in \mathbb{C}P^2: Z^2=XY\}?$