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 r394780 = x;
        double r394781 = 1.0;
        double r394782 = r394780 + r394781;
        double r394783 = sqrt(r394782);
        double r394784 = sqrt(r394780);
        double r394785 = r394783 - r394784;
        double r394786 = y;
        double r394787 = r394786 + r394781;
        double r394788 = sqrt(r394787);
        double r394789 = sqrt(r394786);
        double r394790 = r394788 - r394789;
        double r394791 = r394785 + r394790;
        double r394792 = z;
        double r394793 = r394792 + r394781;
        double r394794 = sqrt(r394793);
        double r394795 = sqrt(r394792);
        double r394796 = r394794 - r394795;
        double r394797 = r394791 + r394796;
        double r394798 = t;
        double r394799 = r394798 + r394781;
        double r394800 = sqrt(r394799);
        double r394801 = sqrt(r394798);
        double r394802 = r394800 - r394801;
        double r394803 = r394797 + r394802;
        return r394803;
}