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 r301899 = x;
        double r301900 = 1.0;
        double r301901 = r301899 + r301900;
        double r301902 = sqrt(r301901);
        double r301903 = sqrt(r301899);
        double r301904 = r301902 - r301903;
        double r301905 = y;
        double r301906 = r301905 + r301900;
        double r301907 = sqrt(r301906);
        double r301908 = sqrt(r301905);
        double r301909 = r301907 - r301908;
        double r301910 = r301904 + r301909;
        double r301911 = z;
        double r301912 = r301911 + r301900;
        double r301913 = sqrt(r301912);
        double r301914 = sqrt(r301911);
        double r301915 = r301913 - r301914;
        double r301916 = r301910 + r301915;
        double r301917 = t;
        double r301918 = r301917 + r301900;
        double r301919 = sqrt(r301918);
        double r301920 = sqrt(r301917);
        double r301921 = r301919 - r301920;
        double r301922 = r301916 + r301921;
        return r301922;
}