//
// Created by wangliewei on 2021/8/12.
//

#include<iostream>
using namespace std;

int main(){

    double x;
    cin >> x;

    bool mark = false;
    if (x < 0) {
        mark = true;
        x = -x;
    }

    double l = 0, r = 1000;
    while (r - l > 1e-8) {
        double mid = (l + r) / 2;
        if (mid * mid * mid >= x) r = mid;
        else l = mid;
    }
    if (mark) printf("-%lf\n", r);
    else printf("%lf\n", r); //double对应lf，表示双精度浮点型

    return 0;
}