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 r518410 = x;
        double r518411 = 1.0;
        double r518412 = r518410 + r518411;
        double r518413 = sqrt(r518412);
        double r518414 = sqrt(r518410);
        double r518415 = r518413 - r518414;
        double r518416 = y;
        double r518417 = r518416 + r518411;
        double r518418 = sqrt(r518417);
        double r518419 = sqrt(r518416);
        double r518420 = r518418 - r518419;
        double r518421 = r518415 + r518420;
        double r518422 = z;
        double r518423 = r518422 + r518411;
        double r518424 = sqrt(r518423);
        double r518425 = sqrt(r518422);
        double r518426 = r518424 - r518425;
        double r518427 = r518421 + r518426;
        double r518428 = t;
        double r518429 = r518428 + r518411;
        double r518430 = sqrt(r518429);
        double r518431 = sqrt(r518428);
        double r518432 = r518430 - r518431;
        double r518433 = r518427 + r518432;
        return r518433;
}