#includ<iostream>
using namespace std;
int main()
{
    double x;
    cin>>x;
    double l=-100,r=100;
    while(r-1>1e-8)
    {
        double mid=(l+r)/2;
        if(mid*mid*mid>x) r=mid;
        else l=mid;
    }
    printf("%lf",l);
    return 0;
}