#include <iostream>
#include <iomanip>

using namespace std;

int main()
{
    //0.027 的立方根是0.3
    double l = -10000.0, r = 10000.0;
    double n;
    cin >> n;
    //样例输出是六位数
    while(r - l > 1e-7)
    {
        double mid = (l + r) / 2.0;
        if (mid * mid * mid > n)
            r = mid;
        else
            l = mid;
    }
    cout << fixed << setprecision(6) << r;
    return 0;
}