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 r561367 = x;
        double r561368 = 1.0;
        double r561369 = r561367 + r561368;
        double r561370 = sqrt(r561369);
        double r561371 = sqrt(r561367);
        double r561372 = r561370 - r561371;
        double r561373 = y;
        double r561374 = r561373 + r561368;
        double r561375 = sqrt(r561374);
        double r561376 = sqrt(r561373);
        double r561377 = r561375 - r561376;
        double r561378 = r561372 + r561377;
        double r561379 = z;
        double r561380 = r561379 + r561368;
        double r561381 = sqrt(r561380);
        double r561382 = sqrt(r561379);
        double r561383 = r561381 - r561382;
        double r561384 = r561378 + r561383;
        double r561385 = t;
        double r561386 = r561385 + r561368;
        double r561387 = sqrt(r561386);
        double r561388 = sqrt(r561385);
        double r561389 = r561387 - r561388;
        double r561390 = r561384 + r561389;
        return r561390;
}