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 r610891 = x;
        double r610892 = 1.0;
        double r610893 = r610891 + r610892;
        double r610894 = sqrt(r610893);
        double r610895 = sqrt(r610891);
        double r610896 = r610894 - r610895;
        double r610897 = y;
        double r610898 = r610897 + r610892;
        double r610899 = sqrt(r610898);
        double r610900 = sqrt(r610897);
        double r610901 = r610899 - r610900;
        double r610902 = r610896 + r610901;
        double r610903 = z;
        double r610904 = r610903 + r610892;
        double r610905 = sqrt(r610904);
        double r610906 = sqrt(r610903);
        double r610907 = r610905 - r610906;
        double r610908 = r610902 + r610907;
        double r610909 = t;
        double r610910 = r610909 + r610892;
        double r610911 = sqrt(r610910);
        double r610912 = sqrt(r610909);
        double r610913 = r610911 - r610912;
        double r610914 = r610908 + r610913;
        return r610914;
}