s = input()
ss = input()
s = s[::-1]
ss = ss[::-1]
a = [0] * 1100
b = [0] * 1100
n = len(s)
m = len(ss)
for i in range(n):
    a[i + 1] = int(s[i])
for i in range(m):
    b[i + 1] = int(ss[i])
n = max(n, m)
for i in range(1, n + 1):
    a[i + 1] += (a[i] + b[i]) // 10
    a[i] = (a[i] + b[i]) % 10
if a[n + 1] != 0:
    n += 1
for i in range(n, 0, -1):
    print(a[i], end='')

这个代码在提交后评测机反馈RE，不知道什么问题，求助