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 r21623485 = x;
        double r21623486 = 1.0;
        double r21623487 = r21623485 + r21623486;
        double r21623488 = sqrt(r21623487);
        double r21623489 = sqrt(r21623485);
        double r21623490 = r21623488 - r21623489;
        double r21623491 = y;
        double r21623492 = r21623491 + r21623486;
        double r21623493 = sqrt(r21623492);
        double r21623494 = sqrt(r21623491);
        double r21623495 = r21623493 - r21623494;
        double r21623496 = r21623490 + r21623495;
        double r21623497 = z;
        double r21623498 = r21623497 + r21623486;
        double r21623499 = sqrt(r21623498);
        double r21623500 = sqrt(r21623497);
        double r21623501 = r21623499 - r21623500;
        double r21623502 = r21623496 + r21623501;
        double r21623503 = t;
        double r21623504 = r21623503 + r21623486;
        double r21623505 = sqrt(r21623504);
        double r21623506 = sqrt(r21623503);
        double r21623507 = r21623505 - r21623506;
        double r21623508 = r21623502 + r21623507;
        return r21623508;
}