#include <iostream>

inline double square(double x) { return x*x; }

double root4(double a) {
	constexpr double eps = 1e-32;
    double x = 0, fx = a/4;
    while (square(fx - x) > eps) {
        x = fx;
        fx = (3*x + a/(x*x*x))/4;
    }
    return fx;
}

int main() {
    for (int i = 0; i < 1000; i++) {
        std::cout << "root4(" << i << ") = " << root4(i) << std::endl;
    }
    return 0;
}