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 r18108316 = x;
        double r18108317 = 1.0;
        double r18108318 = r18108316 + r18108317;
        double r18108319 = sqrt(r18108318);
        double r18108320 = sqrt(r18108316);
        double r18108321 = r18108319 - r18108320;
        double r18108322 = y;
        double r18108323 = r18108322 + r18108317;
        double r18108324 = sqrt(r18108323);
        double r18108325 = sqrt(r18108322);
        double r18108326 = r18108324 - r18108325;
        double r18108327 = r18108321 + r18108326;
        double r18108328 = z;
        double r18108329 = r18108328 + r18108317;
        double r18108330 = sqrt(r18108329);
        double r18108331 = sqrt(r18108328);
        double r18108332 = r18108330 - r18108331;
        double r18108333 = r18108327 + r18108332;
        double r18108334 = t;
        double r18108335 = r18108334 + r18108317;
        double r18108336 = sqrt(r18108335);
        double r18108337 = sqrt(r18108334);
        double r18108338 = r18108336 - r18108337;
        double r18108339 = r18108333 + r18108338;
        return r18108339;
}