#include <iostream>
#include <cstdio>

using namespace std;

int main(){
        int q;
        cin >> q;
        while(q > 0){ 
                double x = q/2;
                while((x*x*x-q)*10000 >= q || (x*x*x-q)*10000 <= -q){
                        x -= (x*x*x-q)/(3*x*x);
                }   
                cout << x << endl;
                cin >> q;
        }   
}