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 r366902 = x;
        double r366903 = 1.0;
        double r366904 = r366902 + r366903;
        double r366905 = sqrt(r366904);
        double r366906 = sqrt(r366902);
        double r366907 = r366905 - r366906;
        double r366908 = y;
        double r366909 = r366908 + r366903;
        double r366910 = sqrt(r366909);
        double r366911 = sqrt(r366908);
        double r366912 = r366910 - r366911;
        double r366913 = r366907 + r366912;
        double r366914 = z;
        double r366915 = r366914 + r366903;
        double r366916 = sqrt(r366915);
        double r366917 = sqrt(r366914);
        double r366918 = r366916 - r366917;
        double r366919 = r366913 + r366918;
        double r366920 = t;
        double r366921 = r366920 + r366903;
        double r366922 = sqrt(r366921);
        double r366923 = sqrt(r366920);
        double r366924 = r366922 - r366923;
        double r366925 = r366919 + r366924;
        return r366925;
}