#include<cstring>
#include<iostream>
#include<algorithm>
using namespace std;
int main()
{
double x;
cin >> X;
double l=-10000,r= 10000;
while (r-1> 1e-8)
double mid=(l+r)/2
{
if (mid * mid *mid >=x)r=mid;
else l = mid;
}
printf("%lf\n",l);
return 0;
}