题解 | #求解立方根#

import sys
while True:
    try:
        n = float(input())
        sig = 1
        #考虑小于0的数,转成正数处理
        if n < 0:
            sig = -1
            n = -n
        #使用二分法查找 
        #考虑小于1的数,起点是n,终点是1
        #大于等于1的数,起点是0,终点是n
        if n < 1:
            start = n 
            end = 1
        else:
            start = 0
            end = n
        g = (start + end) / 2
        while abs(g**3 - n) > 0.01:
#             print(g)
            if g**3 > n:
                end = g 
            else:
                start = g
            g = (start + end) / 2

        print(round(sig*g,1))

    except:
#         print(sys.exc_info())
        break