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 r537605 = x;
        double r537606 = 1.0;
        double r537607 = r537605 + r537606;
        double r537608 = sqrt(r537607);
        double r537609 = sqrt(r537605);
        double r537610 = r537608 - r537609;
        double r537611 = y;
        double r537612 = r537611 + r537606;
        double r537613 = sqrt(r537612);
        double r537614 = sqrt(r537611);
        double r537615 = r537613 - r537614;
        double r537616 = r537610 + r537615;
        double r537617 = z;
        double r537618 = r537617 + r537606;
        double r537619 = sqrt(r537618);
        double r537620 = sqrt(r537617);
        double r537621 = r537619 - r537620;
        double r537622 = r537616 + r537621;
        double r537623 = t;
        double r537624 = r537623 + r537606;
        double r537625 = sqrt(r537624);
        double r537626 = sqrt(r537623);
        double r537627 = r537625 - r537626;
        double r537628 = r537622 + r537627;
        return r537628;
}