#include<iostream>
using namespace std;


double n;


int main()
{
    cin>>n;
    double l = -10000;
    double r = 10000;
    double mid = 0;
    while(r - l > 1e-8)
    {
        mid = (l + r) / 2;
        if(mid * mid * mid > n) r = mid;
        else l = mid;
    }
    printf("%lf", mid);
    return 0;
}