#include<iostream>
using namespace std;
int main()
{
double n,l,r;
cin>>n;
l = -10000,r = 10000;
//当-1<n<1时进行特判
if(n>-1&&n<1) l = -1,r = 1;
while(r - l > 1e-8)
{
double mid = (l + r)/2;
if(mid*mid*mid>n) r = mid;
else l = mid;
}
//printf默认输出六位小数
printf("%lf",l);
return 0;
}
//cbrt()为三次方根函数