a,b=gets.split(" ").map(&:to_i)
bs=b.to_s(2)
as=a.to_s(2).rjust(bs.length,'0')

ans = (
  bs.chars.zip(as.chars).inject(1) do |res,ba|
    bb,aa=ba
    if bb=='1'&&aa=='0'
      res*2
    elsif bb=='0'&&aa=='1'
      res*0
    else
      res
    end
  end
)

if ans==1
  p 1
else
  p ans/2
end