#include<iostream>

using namespace std;

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",r);
    return 0;
}