include[HTML_REMOVED]

using namespace std;
double n;
int main()
{
cin >> n;

double l, r;

l=-10000,r=10000;

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;

}