#include <iostream>
using namespace std;
int main()
{
double x;
scanf("%lf", &x);
double l = -10000, r = 10000;
while(r - l > 1e-8)
{
double mid = (l + r) / 2; // double定义成浮点数, 并且只能用除法不能用位运算
if(mid * mid * mid >= x) r = mid;
else l = mid;
}
printf("%lf", l);
}