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 r301441 = x;
        double r301442 = 1.0;
        double r301443 = r301441 + r301442;
        double r301444 = sqrt(r301443);
        double r301445 = sqrt(r301441);
        double r301446 = r301444 - r301445;
        double r301447 = y;
        double r301448 = r301447 + r301442;
        double r301449 = sqrt(r301448);
        double r301450 = sqrt(r301447);
        double r301451 = r301449 - r301450;
        double r301452 = r301446 + r301451;
        double r301453 = z;
        double r301454 = r301453 + r301442;
        double r301455 = sqrt(r301454);
        double r301456 = sqrt(r301453);
        double r301457 = r301455 - r301456;
        double r301458 = r301452 + r301457;
        double r301459 = t;
        double r301460 = r301459 + r301442;
        double r301461 = sqrt(r301460);
        double r301462 = sqrt(r301459);
        double r301463 = r301461 - r301462;
        double r301464 = r301458 + r301463;
        return r301464;
}