#include <iostream>
using namespace std;
int main(void)
{
    double b;
    scanf("%lf",&b);
    double l = -1e4,r = 1e4;
    while (r - l > 1e-8)
    {
        double m = l + (r - l) / 2;
        if (m * m * m > b)  r = m;
        else    l = m;
    }
    printf("%lf",l);
    return 0;
}