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 r466665 = x;
        double r466666 = 1.0;
        double r466667 = r466665 + r466666;
        double r466668 = sqrt(r466667);
        double r466669 = sqrt(r466665);
        double r466670 = r466668 - r466669;
        double r466671 = y;
        double r466672 = r466671 + r466666;
        double r466673 = sqrt(r466672);
        double r466674 = sqrt(r466671);
        double r466675 = r466673 - r466674;
        double r466676 = r466670 + r466675;
        double r466677 = z;
        double r466678 = r466677 + r466666;
        double r466679 = sqrt(r466678);
        double r466680 = sqrt(r466677);
        double r466681 = r466679 - r466680;
        double r466682 = r466676 + r466681;
        double r466683 = t;
        double r466684 = r466683 + r466666;
        double r466685 = sqrt(r466684);
        double r466686 = sqrt(r466683);
        double r466687 = r466685 - r466686;
        double r466688 = r466682 + r466687;
        return r466688;
}