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 r466645 = x;
        double r466646 = 1.0;
        double r466647 = r466645 + r466646;
        double r466648 = sqrt(r466647);
        double r466649 = sqrt(r466645);
        double r466650 = r466648 - r466649;
        double r466651 = y;
        double r466652 = r466651 + r466646;
        double r466653 = sqrt(r466652);
        double r466654 = sqrt(r466651);
        double r466655 = r466653 - r466654;
        double r466656 = r466650 + r466655;
        double r466657 = z;
        double r466658 = r466657 + r466646;
        double r466659 = sqrt(r466658);
        double r466660 = sqrt(r466657);
        double r466661 = r466659 - r466660;
        double r466662 = r466656 + r466661;
        double r466663 = t;
        double r466664 = r466663 + r466646;
        double r466665 = sqrt(r466664);
        double r466666 = sqrt(r466663);
        double r466667 = r466665 - r466666;
        double r466668 = r466662 + r466667;
        return r466668;
}