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 r415603 = x;
        double r415604 = 1.0;
        double r415605 = r415603 + r415604;
        double r415606 = sqrt(r415605);
        double r415607 = sqrt(r415603);
        double r415608 = r415606 - r415607;
        double r415609 = y;
        double r415610 = r415609 + r415604;
        double r415611 = sqrt(r415610);
        double r415612 = sqrt(r415609);
        double r415613 = r415611 - r415612;
        double r415614 = r415608 + r415613;
        double r415615 = z;
        double r415616 = r415615 + r415604;
        double r415617 = sqrt(r415616);
        double r415618 = sqrt(r415615);
        double r415619 = r415617 - r415618;
        double r415620 = r415614 + r415619;
        double r415621 = t;
        double r415622 = r415621 + r415604;
        double r415623 = sqrt(r415622);
        double r415624 = sqrt(r415621);
        double r415625 = r415623 - r415624;
        double r415626 = r415620 + r415625;
        return r415626;
}