#!/usr/bin/env python3

def go(x, y, i):
    while x[i-1]+y[i-1] == 9: i -= 1
    l = max(j for j in D if x[j])
    return [((-(j<l)-x[j]) % 10)*(j >= i) for j in D]

x = [0]+list(map(int, input()))
y = [0]+list(map(int, input()))
d = len(x)-len(y)
if d > 0: y = [0]*d + y
else: x = [0]*(-d) + x
D = range(len(x))
i = next((i for i in D if x[i] + y[i] >= 10), -1)
print(''.join(map(str, min(go(x, y, i), go(y, x, i)))).lstrip('0') if i >= 0 else '0')