题解 | #求解立方根#

def cube_root_newton(val, tolerance=1e-4):
    x = val
    while abs(x**3 - val) >= tolerance:
        x = 2*x/3 + val/(3*x**2)
    return round(x, 1)

# 读取输入
val = float(input().strip())

# 计算立方根并输出
print(cube_root_newton(val))