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 r279854 = x;
        double r279855 = 1.0;
        double r279856 = r279854 + r279855;
        double r279857 = sqrt(r279856);
        double r279858 = sqrt(r279854);
        double r279859 = r279857 - r279858;
        double r279860 = y;
        double r279861 = r279860 + r279855;
        double r279862 = sqrt(r279861);
        double r279863 = sqrt(r279860);
        double r279864 = r279862 - r279863;
        double r279865 = r279859 + r279864;
        double r279866 = z;
        double r279867 = r279866 + r279855;
        double r279868 = sqrt(r279867);
        double r279869 = sqrt(r279866);
        double r279870 = r279868 - r279869;
        double r279871 = r279865 + r279870;
        double r279872 = t;
        double r279873 = r279872 + r279855;
        double r279874 = sqrt(r279873);
        double r279875 = sqrt(r279872);
        double r279876 = r279874 - r279875;
        double r279877 = r279871 + r279876;
        return r279877;
}