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 r543391 = x;
        double r543392 = 1.0;
        double r543393 = r543391 + r543392;
        double r543394 = sqrt(r543393);
        double r543395 = sqrt(r543391);
        double r543396 = r543394 - r543395;
        double r543397 = y;
        double r543398 = r543397 + r543392;
        double r543399 = sqrt(r543398);
        double r543400 = sqrt(r543397);
        double r543401 = r543399 - r543400;
        double r543402 = r543396 + r543401;
        double r543403 = z;
        double r543404 = r543403 + r543392;
        double r543405 = sqrt(r543404);
        double r543406 = sqrt(r543403);
        double r543407 = r543405 - r543406;
        double r543408 = r543402 + r543407;
        double r543409 = t;
        double r543410 = r543409 + r543392;
        double r543411 = sqrt(r543410);
        double r543412 = sqrt(r543409);
        double r543413 = r543411 - r543412;
        double r543414 = r543408 + r543413;
        return r543414;
}