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 r480246 = x;
        double r480247 = 1.0;
        double r480248 = r480246 + r480247;
        double r480249 = sqrt(r480248);
        double r480250 = sqrt(r480246);
        double r480251 = r480249 - r480250;
        double r480252 = y;
        double r480253 = r480252 + r480247;
        double r480254 = sqrt(r480253);
        double r480255 = sqrt(r480252);
        double r480256 = r480254 - r480255;
        double r480257 = r480251 + r480256;
        double r480258 = z;
        double r480259 = r480258 + r480247;
        double r480260 = sqrt(r480259);
        double r480261 = sqrt(r480258);
        double r480262 = r480260 - r480261;
        double r480263 = r480257 + r480262;
        double r480264 = t;
        double r480265 = r480264 + r480247;
        double r480266 = sqrt(r480265);
        double r480267 = sqrt(r480264);
        double r480268 = r480266 - r480267;
        double r480269 = r480263 + r480268;
        return r480269;
}