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 r21018247 = x;
        double r21018248 = 1.0;
        double r21018249 = r21018247 + r21018248;
        double r21018250 = sqrt(r21018249);
        double r21018251 = sqrt(r21018247);
        double r21018252 = r21018250 - r21018251;
        double r21018253 = y;
        double r21018254 = r21018253 + r21018248;
        double r21018255 = sqrt(r21018254);
        double r21018256 = sqrt(r21018253);
        double r21018257 = r21018255 - r21018256;
        double r21018258 = r21018252 + r21018257;
        double r21018259 = z;
        double r21018260 = r21018259 + r21018248;
        double r21018261 = sqrt(r21018260);
        double r21018262 = sqrt(r21018259);
        double r21018263 = r21018261 - r21018262;
        double r21018264 = r21018258 + r21018263;
        double r21018265 = t;
        double r21018266 = r21018265 + r21018248;
        double r21018267 = sqrt(r21018266);
        double r21018268 = sqrt(r21018265);
        double r21018269 = r21018267 - r21018268;
        double r21018270 = r21018264 + r21018269;
        return r21018270;
}