# Arup Guha
# 8/30/2022
# Alternate Solution to 2022 UCF Locals Qualifying Round Problem: Decimal XOR

# How dexor is defined in the problem.
def dexor(a,b):
    if a<=2 and b<=2:
        return 0
    if a>=7 and b>=7:
        return 0
    return 9

def main():

    # Read input.
    x = input()
    y = input()
    sz = max(len(x), len(y))

    # Pad so both the same size.
    while len(x) < sz:
        x = "0"+x
    while len(y) < sz:
        y = "0"+y

    # Python makes this annoying.
    for i in range(sz):
        print(dexor(ord(x[i])-ord('0'), ord(y[i])-ord('0')), end="")
    print()

# Run it!
main()