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 r502139 = x;
        double r502140 = 1.0;
        double r502141 = r502139 + r502140;
        double r502142 = sqrt(r502141);
        double r502143 = sqrt(r502139);
        double r502144 = r502142 - r502143;
        double r502145 = y;
        double r502146 = r502145 + r502140;
        double r502147 = sqrt(r502146);
        double r502148 = sqrt(r502145);
        double r502149 = r502147 - r502148;
        double r502150 = r502144 + r502149;
        double r502151 = z;
        double r502152 = r502151 + r502140;
        double r502153 = sqrt(r502152);
        double r502154 = sqrt(r502151);
        double r502155 = r502153 - r502154;
        double r502156 = r502150 + r502155;
        double r502157 = t;
        double r502158 = r502157 + r502140;
        double r502159 = sqrt(r502158);
        double r502160 = sqrt(r502157);
        double r502161 = r502159 - r502160;
        double r502162 = r502156 + r502161;
        return r502162;
}