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 r507005 = x;
        double r507006 = 1.0;
        double r507007 = r507005 + r507006;
        double r507008 = sqrt(r507007);
        double r507009 = sqrt(r507005);
        double r507010 = r507008 - r507009;
        double r507011 = y;
        double r507012 = r507011 + r507006;
        double r507013 = sqrt(r507012);
        double r507014 = sqrt(r507011);
        double r507015 = r507013 - r507014;
        double r507016 = r507010 + r507015;
        double r507017 = z;
        double r507018 = r507017 + r507006;
        double r507019 = sqrt(r507018);
        double r507020 = sqrt(r507017);
        double r507021 = r507019 - r507020;
        double r507022 = r507016 + r507021;
        double r507023 = t;
        double r507024 = r507023 + r507006;
        double r507025 = sqrt(r507024);
        double r507026 = sqrt(r507023);
        double r507027 = r507025 - r507026;
        double r507028 = r507022 + r507027;
        return r507028;
}