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 r375771 = x;
        double r375772 = 1.0;
        double r375773 = r375771 + r375772;
        double r375774 = sqrt(r375773);
        double r375775 = sqrt(r375771);
        double r375776 = r375774 - r375775;
        double r375777 = y;
        double r375778 = r375777 + r375772;
        double r375779 = sqrt(r375778);
        double r375780 = sqrt(r375777);
        double r375781 = r375779 - r375780;
        double r375782 = r375776 + r375781;
        double r375783 = z;
        double r375784 = r375783 + r375772;
        double r375785 = sqrt(r375784);
        double r375786 = sqrt(r375783);
        double r375787 = r375785 - r375786;
        double r375788 = r375782 + r375787;
        double r375789 = t;
        double r375790 = r375789 + r375772;
        double r375791 = sqrt(r375790);
        double r375792 = sqrt(r375789);
        double r375793 = r375791 - r375792;
        double r375794 = r375788 + r375793;
        return r375794;
}