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 r371718 = x;
        double r371719 = 1.0;
        double r371720 = r371718 + r371719;
        double r371721 = sqrt(r371720);
        double r371722 = sqrt(r371718);
        double r371723 = r371721 - r371722;
        double r371724 = y;
        double r371725 = r371724 + r371719;
        double r371726 = sqrt(r371725);
        double r371727 = sqrt(r371724);
        double r371728 = r371726 - r371727;
        double r371729 = r371723 + r371728;
        double r371730 = z;
        double r371731 = r371730 + r371719;
        double r371732 = sqrt(r371731);
        double r371733 = sqrt(r371730);
        double r371734 = r371732 - r371733;
        double r371735 = r371729 + r371734;
        double r371736 = t;
        double r371737 = r371736 + r371719;
        double r371738 = sqrt(r371737);
        double r371739 = sqrt(r371736);
        double r371740 = r371738 - r371739;
        double r371741 = r371735 + r371740;
        return r371741;
}