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 r305013 = x;
        double r305014 = 1.0;
        double r305015 = r305013 + r305014;
        double r305016 = sqrt(r305015);
        double r305017 = sqrt(r305013);
        double r305018 = r305016 - r305017;
        double r305019 = y;
        double r305020 = r305019 + r305014;
        double r305021 = sqrt(r305020);
        double r305022 = sqrt(r305019);
        double r305023 = r305021 - r305022;
        double r305024 = r305018 + r305023;
        double r305025 = z;
        double r305026 = r305025 + r305014;
        double r305027 = sqrt(r305026);
        double r305028 = sqrt(r305025);
        double r305029 = r305027 - r305028;
        double r305030 = r305024 + r305029;
        double r305031 = t;
        double r305032 = r305031 + r305014;
        double r305033 = sqrt(r305032);
        double r305034 = sqrt(r305031);
        double r305035 = r305033 - r305034;
        double r305036 = r305030 + r305035;
        return r305036;
}