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 r263468 = x;
        double r263469 = 1.0;
        double r263470 = r263468 + r263469;
        double r263471 = sqrt(r263470);
        double r263472 = sqrt(r263468);
        double r263473 = r263471 - r263472;
        double r263474 = y;
        double r263475 = r263474 + r263469;
        double r263476 = sqrt(r263475);
        double r263477 = sqrt(r263474);
        double r263478 = r263476 - r263477;
        double r263479 = r263473 + r263478;
        double r263480 = z;
        double r263481 = r263480 + r263469;
        double r263482 = sqrt(r263481);
        double r263483 = sqrt(r263480);
        double r263484 = r263482 - r263483;
        double r263485 = r263479 + r263484;
        double r263486 = t;
        double r263487 = r263486 + r263469;
        double r263488 = sqrt(r263487);
        double r263489 = sqrt(r263486);
        double r263490 = r263488 - r263489;
        double r263491 = r263485 + r263490;
        return r263491;
}