// 常规的二分法,注意
//(1)输入值为负数;
//(2)输入值在0-1之间;
using System;
class Solution{
public static void Main(){
double input = Convert.ToDouble(Console.ReadLine());
double res = GetValue(input);
Console.WriteLine(res.ToString());
}
public static double GetValue(double input){
double input_1 = Math.Abs(input);//输入值为负数,结果取负数
double left = 0;
double right = Math.Max(input_1,1);//若输入值为0-1,则右边界为1
while (right -left > 0.001){
double mid = left + (right-left)/2;
if(mid*mid*mid < input_1){
left = mid;
}else{
right = mid;
}
}
if(input<0){
left = -left;
}
return Math.Round(left,1);
}
}