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 r480899 = x;
        double r480900 = 1.0;
        double r480901 = r480899 + r480900;
        double r480902 = sqrt(r480901);
        double r480903 = sqrt(r480899);
        double r480904 = r480902 - r480903;
        double r480905 = y;
        double r480906 = r480905 + r480900;
        double r480907 = sqrt(r480906);
        double r480908 = sqrt(r480905);
        double r480909 = r480907 - r480908;
        double r480910 = r480904 + r480909;
        double r480911 = z;
        double r480912 = r480911 + r480900;
        double r480913 = sqrt(r480912);
        double r480914 = sqrt(r480911);
        double r480915 = r480913 - r480914;
        double r480916 = r480910 + r480915;
        double r480917 = t;
        double r480918 = r480917 + r480900;
        double r480919 = sqrt(r480918);
        double r480920 = sqrt(r480917);
        double r480921 = r480919 - r480920;
        double r480922 = r480916 + r480921;
        return r480922;
}