Cannot sample enough valid points. (more)

\[\left(\left(\left(\sqrt{x + 1} - \sqrt{x}\right) + \left(\sqrt{y + 1} - \sqrt{y}\right)\right) + \left(\sqrt{z + 1} - \sqrt{z}\right)\right) + \left(\sqrt{t + 1} - \sqrt{t}\right)\]
\left(\left(\left(\sqrt{x + 1} - \sqrt{x}\right) + \left(\sqrt{y + 1} - \sqrt{y}\right)\right) + \left(\sqrt{z + 1} - \sqrt{z}\right)\right) + \left(\sqrt{t + 1} - \sqrt{t}\right)
double f(double x, double y, double z, double t) {
        double r501926 = x;
        double r501927 = 1.0;
        double r501928 = r501926 + r501927;
        double r501929 = sqrt(r501928);
        double r501930 = sqrt(r501926);
        double r501931 = r501929 - r501930;
        double r501932 = y;
        double r501933 = r501932 + r501927;
        double r501934 = sqrt(r501933);
        double r501935 = sqrt(r501932);
        double r501936 = r501934 - r501935;
        double r501937 = r501931 + r501936;
        double r501938 = z;
        double r501939 = r501938 + r501927;
        double r501940 = sqrt(r501939);
        double r501941 = sqrt(r501938);
        double r501942 = r501940 - r501941;
        double r501943 = r501937 + r501942;
        double r501944 = t;
        double r501945 = r501944 + r501927;
        double r501946 = sqrt(r501945);
        double r501947 = sqrt(r501944);
        double r501948 = r501946 - r501947;
        double r501949 = r501943 + r501948;
        return r501949;
}