题解 | #求解立方根#

import sys

n = float(input())
left = -3
right = 3
while True:
    if str(n) in str(left**3):
        print("%.1f" % left)
        break
    elif str(n) in str(right**3):
        print("%.1f" % right)
        break
    else:
        mid = (left+right)/2
        if mid**3 > n:
            right = mid
        elif mid**3 < n:
            left = mid
        else:
            print("%.1f" % mid)
            break