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 r447447 = x;
        double r447448 = 1.0;
        double r447449 = r447447 + r447448;
        double r447450 = sqrt(r447449);
        double r447451 = sqrt(r447447);
        double r447452 = r447450 - r447451;
        double r447453 = y;
        double r447454 = r447453 + r447448;
        double r447455 = sqrt(r447454);
        double r447456 = sqrt(r447453);
        double r447457 = r447455 - r447456;
        double r447458 = r447452 + r447457;
        double r447459 = z;
        double r447460 = r447459 + r447448;
        double r447461 = sqrt(r447460);
        double r447462 = sqrt(r447459);
        double r447463 = r447461 - r447462;
        double r447464 = r447458 + r447463;
        double r447465 = t;
        double r447466 = r447465 + r447448;
        double r447467 = sqrt(r447466);
        double r447468 = sqrt(r447465);
        double r447469 = r447467 - r447468;
        double r447470 = r447464 + r447469;
        return r447470;
}