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 r518842 = x;
        double r518843 = 1.0;
        double r518844 = r518842 + r518843;
        double r518845 = sqrt(r518844);
        double r518846 = sqrt(r518842);
        double r518847 = r518845 - r518846;
        double r518848 = y;
        double r518849 = r518848 + r518843;
        double r518850 = sqrt(r518849);
        double r518851 = sqrt(r518848);
        double r518852 = r518850 - r518851;
        double r518853 = r518847 + r518852;
        double r518854 = z;
        double r518855 = r518854 + r518843;
        double r518856 = sqrt(r518855);
        double r518857 = sqrt(r518854);
        double r518858 = r518856 - r518857;
        double r518859 = r518853 + r518858;
        double r518860 = t;
        double r518861 = r518860 + r518843;
        double r518862 = sqrt(r518861);
        double r518863 = sqrt(r518860);
        double r518864 = r518862 - r518863;
        double r518865 = r518859 + r518864;
        return r518865;
}