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 r30120 = x;
        double r30121 = 1.0;
        double r30122 = r30120 + r30121;
        double r30123 = sqrt(r30122);
        double r30124 = sqrt(r30120);
        double r30125 = r30123 - r30124;
        double r30126 = y;
        double r30127 = r30126 + r30121;
        double r30128 = sqrt(r30127);
        double r30129 = sqrt(r30126);
        double r30130 = r30128 - r30129;
        double r30131 = r30125 + r30130;
        double r30132 = z;
        double r30133 = r30132 + r30121;
        double r30134 = sqrt(r30133);
        double r30135 = sqrt(r30132);
        double r30136 = r30134 - r30135;
        double r30137 = r30131 + r30136;
        double r30138 = t;
        double r30139 = r30138 + r30121;
        double r30140 = sqrt(r30139);
        double r30141 = sqrt(r30138);
        double r30142 = r30140 - r30141;
        double r30143 = r30137 + r30142;
        return r30143;
}