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 r541382 = x;
        double r541383 = 1.0;
        double r541384 = r541382 + r541383;
        double r541385 = sqrt(r541384);
        double r541386 = sqrt(r541382);
        double r541387 = r541385 - r541386;
        double r541388 = y;
        double r541389 = r541388 + r541383;
        double r541390 = sqrt(r541389);
        double r541391 = sqrt(r541388);
        double r541392 = r541390 - r541391;
        double r541393 = r541387 + r541392;
        double r541394 = z;
        double r541395 = r541394 + r541383;
        double r541396 = sqrt(r541395);
        double r541397 = sqrt(r541394);
        double r541398 = r541396 - r541397;
        double r541399 = r541393 + r541398;
        double r541400 = t;
        double r541401 = r541400 + r541383;
        double r541402 = sqrt(r541401);
        double r541403 = sqrt(r541400);
        double r541404 = r541402 - r541403;
        double r541405 = r541399 + r541404;
        return r541405;
}