写了个输入计算精度，求e近似值的算法，请问下为什么会在第八行报错，及如何修改

Question

写了个输入计算精度，求e近似值的算法，请问下为什么会在第八行报错，及如何修改

原算法：

def factorial(a):
    if a == 1:
        return a
    else:
        return (a * factorial(a - 1))
b = 1
c = 1
while b <= int(input()):
    c = c + 1 / factorial(b)
    b = b + 1
print(c)

报错结果：

line 8, in <module>
    while b <= int(input()):
ValueError: invalid literal for int() with base 10: ''

Answer 1

def fac(x):
    if x == 1 or x == 0:
        return x
    else:
        return x * fac(x - 1)


i = 1
s = 1
a = eval(input()) #精度
while 1 / fac(i) >= a:
    s = s + 1 / fac(i)
    i += 1
s = s + 1 / fac(i)
print(s)