include [HTML_REMOVED]

using namespace std;

int main()
{
double x ;
cin >>x;
double l = -10010 , r = 10010;

 while (r - l >= 1e-7) {
     double mid = (l + r) /2;
     if (mid * mid * mid >= x) r = mid; 
     else l = mid;
 }
 printf("%.6lf",l);

 return 0;

}