import java.util.*;
public class Main{
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
double num = sc.nextDouble();
boolean flag = false;
if(num < 0) {
flag = true;
num = -num;
}
double l = 0d, r = 100d;
while (r - l > 1e-8) {
double mid = (l + r) / 2;
if(mid * mid * mid < num) {
l = mid;
} else {
r = mid;
}
}
System.out.println(String.format("%.6f", flag? -l:l));
}
}