#include<bits/stdc++.h>
using namespace std;
int main()
{
	double x;
	cin>>x;
	double l=-1000,r=1000;
	while(r-l>1e-9)
	{
		double mid=(r+l)/2.0;
		if(mid*mid*mid<x)
		{
			l=mid;
		}
		else r=mid;
	}
	printf("%.6lf",r);
    return 0;
}