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 r396850 = x;
        double r396851 = 1.0;
        double r396852 = r396850 + r396851;
        double r396853 = sqrt(r396852);
        double r396854 = sqrt(r396850);
        double r396855 = r396853 - r396854;
        double r396856 = y;
        double r396857 = r396856 + r396851;
        double r396858 = sqrt(r396857);
        double r396859 = sqrt(r396856);
        double r396860 = r396858 - r396859;
        double r396861 = r396855 + r396860;
        double r396862 = z;
        double r396863 = r396862 + r396851;
        double r396864 = sqrt(r396863);
        double r396865 = sqrt(r396862);
        double r396866 = r396864 - r396865;
        double r396867 = r396861 + r396866;
        double r396868 = t;
        double r396869 = r396868 + r396851;
        double r396870 = sqrt(r396869);
        double r396871 = sqrt(r396868);
        double r396872 = r396870 - r396871;
        double r396873 = r396867 + r396872;
        return r396873;
}