A, B = gets.split.map(&:to_i)

len = Math.log2(B).floor + 1

xorA = (len-1).downto(0).map do |i|
  if i == 0
    a = A % 4; b = B % 4
    [0, 1, 0, 1, 0, 1, 0, 1][a, (4+b)-a+1].reduce(&:+) % 2
  else
    a = A % (2**(i+1)); b = B % (2**(i+1))
    ((a <= 2**i ? 2**i : 2**(i+1) - a) + (b < 2**i ? 0 : b - 2**i + 1)) % 2
  end
end

ans = xorA.join("").to_i(2)

print("#{ans}\n")