#include<iostream>
#include<iomanip>
using namespace std;
int main() {
double n; cin >> n;
double l=-100, r=100,mid;
if (n < 0) { n = -n; cout << '-'; }
while (r - l > 1e-8) {
mid = (l + r) / 2;
if (mid * mid * mid >= n)r = mid;
else l = mid;
}
cout << fixed << setprecision(6) << mid;
return 0;
}