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 r411888 = x;
        double r411889 = 1.0;
        double r411890 = r411888 + r411889;
        double r411891 = sqrt(r411890);
        double r411892 = sqrt(r411888);
        double r411893 = r411891 - r411892;
        double r411894 = y;
        double r411895 = r411894 + r411889;
        double r411896 = sqrt(r411895);
        double r411897 = sqrt(r411894);
        double r411898 = r411896 - r411897;
        double r411899 = r411893 + r411898;
        double r411900 = z;
        double r411901 = r411900 + r411889;
        double r411902 = sqrt(r411901);
        double r411903 = sqrt(r411900);
        double r411904 = r411902 - r411903;
        double r411905 = r411899 + r411904;
        double r411906 = t;
        double r411907 = r411906 + r411889;
        double r411908 = sqrt(r411907);
        double r411909 = sqrt(r411906);
        double r411910 = r411908 - r411909;
        double r411911 = r411905 + r411910;
        return r411911;
}