#include <iostream>
#include <cstring>
#include <algorithm>
using namespace std;

int main(){
    double n;
    cin >> n;
    double l = -10001, r = 10001;
    while (r - l >= 1e-7){
        double mid = (l + r) / 2;
        if((mid*mid*mid) > n)r = mid;
        else l = mid;
    }
    printf("%lf", l);
    return 0;
}