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 r18537772 = x;
        double r18537773 = 1.0;
        double r18537774 = r18537772 + r18537773;
        double r18537775 = sqrt(r18537774);
        double r18537776 = sqrt(r18537772);
        double r18537777 = r18537775 - r18537776;
        double r18537778 = y;
        double r18537779 = r18537778 + r18537773;
        double r18537780 = sqrt(r18537779);
        double r18537781 = sqrt(r18537778);
        double r18537782 = r18537780 - r18537781;
        double r18537783 = r18537777 + r18537782;
        double r18537784 = z;
        double r18537785 = r18537784 + r18537773;
        double r18537786 = sqrt(r18537785);
        double r18537787 = sqrt(r18537784);
        double r18537788 = r18537786 - r18537787;
        double r18537789 = r18537783 + r18537788;
        double r18537790 = t;
        double r18537791 = r18537790 + r18537773;
        double r18537792 = sqrt(r18537791);
        double r18537793 = sqrt(r18537790);
        double r18537794 = r18537792 - r18537793;
        double r18537795 = r18537789 + r18537794;
        return r18537795;
}