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 r323271 = x;
        double r323272 = 1.0;
        double r323273 = r323271 + r323272;
        double r323274 = sqrt(r323273);
        double r323275 = sqrt(r323271);
        double r323276 = r323274 - r323275;
        double r323277 = y;
        double r323278 = r323277 + r323272;
        double r323279 = sqrt(r323278);
        double r323280 = sqrt(r323277);
        double r323281 = r323279 - r323280;
        double r323282 = r323276 + r323281;
        double r323283 = z;
        double r323284 = r323283 + r323272;
        double r323285 = sqrt(r323284);
        double r323286 = sqrt(r323283);
        double r323287 = r323285 - r323286;
        double r323288 = r323282 + r323287;
        double r323289 = t;
        double r323290 = r323289 + r323272;
        double r323291 = sqrt(r323290);
        double r323292 = sqrt(r323289);
        double r323293 = r323291 - r323292;
        double r323294 = r323288 + r323293;
        return r323294;
}