Assume we classify our points using a Bayesian optimal classifier, CB$($X$),$ corresponding to the conditional class probability P$($Y$=1|$X$=$x$)=\backslash$sigma $(3+$x$1+$x$2),$ where $\backslash$sigma is the sigmoidal function $\backslash$sigma $($z$)=$e$^$z$/(1+$e$^$z$).$ What is the number of false positives? Hint: A sigmoidal function takes the value $1/2$ when its argument is $0.$