#include <iostream>

using namespace std;

double n;

int main()
{
    int l=-10000,r=10000;

    scanf("%lf",&n);
    while(r-l>1e-8)
    {
        double mid =(l+r)/2;
        if(mid*mid*mid>n) r=mid;
        else
        l=mid;
    }

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

double不会报错，还未解决