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 r469770 = x;
        double r469771 = 1.0;
        double r469772 = r469770 + r469771;
        double r469773 = sqrt(r469772);
        double r469774 = sqrt(r469770);
        double r469775 = r469773 - r469774;
        double r469776 = y;
        double r469777 = r469776 + r469771;
        double r469778 = sqrt(r469777);
        double r469779 = sqrt(r469776);
        double r469780 = r469778 - r469779;
        double r469781 = r469775 + r469780;
        double r469782 = z;
        double r469783 = r469782 + r469771;
        double r469784 = sqrt(r469783);
        double r469785 = sqrt(r469782);
        double r469786 = r469784 - r469785;
        double r469787 = r469781 + r469786;
        double r469788 = t;
        double r469789 = r469788 + r469771;
        double r469790 = sqrt(r469789);
        double r469791 = sqrt(r469788);
        double r469792 = r469790 - r469791;
        double r469793 = r469787 + r469792;
        return r469793;
}