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 r519006 = x;
        double r519007 = 1.0;
        double r519008 = r519006 + r519007;
        double r519009 = sqrt(r519008);
        double r519010 = sqrt(r519006);
        double r519011 = r519009 - r519010;
        double r519012 = y;
        double r519013 = r519012 + r519007;
        double r519014 = sqrt(r519013);
        double r519015 = sqrt(r519012);
        double r519016 = r519014 - r519015;
        double r519017 = r519011 + r519016;
        double r519018 = z;
        double r519019 = r519018 + r519007;
        double r519020 = sqrt(r519019);
        double r519021 = sqrt(r519018);
        double r519022 = r519020 - r519021;
        double r519023 = r519017 + r519022;
        double r519024 = t;
        double r519025 = r519024 + r519007;
        double r519026 = sqrt(r519025);
        double r519027 = sqrt(r519024);
        double r519028 = r519026 - r519027;
        double r519029 = r519023 + r519028;
        return r519029;
}