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 r456525 = x;
        double r456526 = 1.0;
        double r456527 = r456525 + r456526;
        double r456528 = sqrt(r456527);
        double r456529 = sqrt(r456525);
        double r456530 = r456528 - r456529;
        double r456531 = y;
        double r456532 = r456531 + r456526;
        double r456533 = sqrt(r456532);
        double r456534 = sqrt(r456531);
        double r456535 = r456533 - r456534;
        double r456536 = r456530 + r456535;
        double r456537 = z;
        double r456538 = r456537 + r456526;
        double r456539 = sqrt(r456538);
        double r456540 = sqrt(r456537);
        double r456541 = r456539 - r456540;
        double r456542 = r456536 + r456541;
        double r456543 = t;
        double r456544 = r456543 + r456526;
        double r456545 = sqrt(r456544);
        double r456546 = sqrt(r456543);
        double r456547 = r456545 - r456546;
        double r456548 = r456542 + r456547;
        return r456548;
}