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 r419103 = x;
        double r419104 = 1.0;
        double r419105 = r419103 + r419104;
        double r419106 = sqrt(r419105);
        double r419107 = sqrt(r419103);
        double r419108 = r419106 - r419107;
        double r419109 = y;
        double r419110 = r419109 + r419104;
        double r419111 = sqrt(r419110);
        double r419112 = sqrt(r419109);
        double r419113 = r419111 - r419112;
        double r419114 = r419108 + r419113;
        double r419115 = z;
        double r419116 = r419115 + r419104;
        double r419117 = sqrt(r419116);
        double r419118 = sqrt(r419115);
        double r419119 = r419117 - r419118;
        double r419120 = r419114 + r419119;
        double r419121 = t;
        double r419122 = r419121 + r419104;
        double r419123 = sqrt(r419122);
        double r419124 = sqrt(r419121);
        double r419125 = r419123 - r419124;
        double r419126 = r419120 + r419125;
        return r419126;
}