a = f"{input():0>30}"  # f文字列で30桁左側0で埋めた表記
b = f"{input():0>30}"

c = [None] * 30

for i in range(30):
    if a[i] == b[i]:
        c[i] = "0"
    else:
        c[i] = "1"

c = "".join(c)

c_2 = int(c, 2)  # int(文字列, 2) で文字列を2進数表記

print(c_2)