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 r401159 = x;
        double r401160 = 1.0;
        double r401161 = r401159 + r401160;
        double r401162 = sqrt(r401161);
        double r401163 = sqrt(r401159);
        double r401164 = r401162 - r401163;
        double r401165 = y;
        double r401166 = r401165 + r401160;
        double r401167 = sqrt(r401166);
        double r401168 = sqrt(r401165);
        double r401169 = r401167 - r401168;
        double r401170 = r401164 + r401169;
        double r401171 = z;
        double r401172 = r401171 + r401160;
        double r401173 = sqrt(r401172);
        double r401174 = sqrt(r401171);
        double r401175 = r401173 - r401174;
        double r401176 = r401170 + r401175;
        double r401177 = t;
        double r401178 = r401177 + r401160;
        double r401179 = sqrt(r401178);
        double r401180 = sqrt(r401177);
        double r401181 = r401179 - r401180;
        double r401182 = r401176 + r401181;
        return r401182;
}