#include <iostream>
using namespace std;

int n;
int main(){
    cin >> n;
    double l = -10001;
    double r = 10001;
    double mid;
    while(r - l > 1e-7){
        mid = (l+r) / 2;
        if((mid*mid*mid) >= n) r = mid;
        else l = mid;
    }

    printf("%.6lf", l);

    return 0;
}