A, B = gets.split(" ").map{|s| s.to_i}

def bitCount(bits)
	bits = (bits & 0x55555555) + ((bits >> 1) & 0x55555555)
	bits = (bits & 0x33333333) + ((bits >> 2) & 0x33333333)
	bits = (bits & 0x0f0f0f0f) + ((bits >> 4) & 0x0f0f0f0f)
	bits = (bits & 0x00ff00ff) + ((bits >> 8) & 0x00ff00ff)
	(bits & 0x0000ffff) + ((bits >> 16) & 0x0000ffff)
end

if A & B != A then
	puts 0
else
	n = bitCount(A ^ B)
	if n < 2 then
		puts 1
	else
		puts 2**(n-1)
	end
end