/*二分查找*/
#include<iostream>
using namespace std;
double n;
int main(){
cin>>n;
if(n==0)cout<<0.000000<<endl;
if(n>0){
double l=0,r=10000;
while(r-l>1e-8){
double mid = (r+l)/2;
if(mid*mid*mid>n)r=mid;
else l=mid;
}
printf("%0.6lf",l);
}
else{
double l=-10000,r=0;
while(r-l>1e-8){
double mid = (r+l)/2;
if(mid*mid*mid>n)r=mid;
else l=mid;
}
printf("%0.6lf",l);
}
return 0;
}