#include <cmath>
#include <iomanip>
#include <iostream>
 
using namespace std;
 
int main()
{
  int a;
 
  while(cin >> a)
  {
    if(a == -1) { goto Exit; }
 
    cout << setprecision(15) << pow(a, 1.0 / 3.0) << endl;
  }
 
Exit:;
 
  return 0;
}