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 r321923 = x;
        double r321924 = 1.0;
        double r321925 = r321923 + r321924;
        double r321926 = sqrt(r321925);
        double r321927 = sqrt(r321923);
        double r321928 = r321926 - r321927;
        double r321929 = y;
        double r321930 = r321929 + r321924;
        double r321931 = sqrt(r321930);
        double r321932 = sqrt(r321929);
        double r321933 = r321931 - r321932;
        double r321934 = r321928 + r321933;
        double r321935 = z;
        double r321936 = r321935 + r321924;
        double r321937 = sqrt(r321936);
        double r321938 = sqrt(r321935);
        double r321939 = r321937 - r321938;
        double r321940 = r321934 + r321939;
        double r321941 = t;
        double r321942 = r321941 + r321924;
        double r321943 = sqrt(r321942);
        double r321944 = sqrt(r321941);
        double r321945 = r321943 - r321944;
        double r321946 = r321940 + r321945;
        return r321946;
}