''' 解题思路: 二分法,定义函数f(x)=y,输入值为y,定义一个初始区间x1、x2,中间值为xm=(x1+x2)/2, 如(f(x1)-y)*(f(xm)-y)>0,则x1=xm,否则x2=xm 要特别注意初始值x1、x2选择,本题有1、-1的约束,因为0.001**(1/3) = 0.1 ''' while 1: try: y = float(input()) x1 = 0.0 if y>0: x2 = max(y,1) else: x2 = min(y,-1) f = lambda x:x**3 k = 0 while abs(x1-x2) > 1e-4: x0 = (x1+x2)/2 if (f(x1)-y)*(f(x0)-y)>0: x1 = x0 else: x2 = x0 k += 1 print(round(x1*10)/10) except: break