#include<bits/stdc++.h>

using namespace std;

int main(){
    double n;
    cin>>n;
    double l = -30, r = 30;
    while(r - l > 1e-8){
        double mid = (l + r) / 2;
        if(mid*mid*mid < n){
            l = mid;
        }
        else if(mid*mid*mid > n){
            r = mid;
        }
    }
    printf("%lf", r);
    return 0;
}