#include <iostream>

using namespace std;

// const int N = 1e-8; //写成常量定义会TLE！！

int main () {
    double x;
    cin >> x;
    double l = -10000, r = 10000;
    while (r - l > 1e-8) {
        double mid = (l + r ) / 2;
        if (mid * mid * mid >= x) r = mid;
        else l = mid;
    }

    printf("%lf\n", l);
    return 0;
}