class Combi
  def initialize(max_n, mod = 10**9+7)
      @mod = mod
      @max_n = max_n

      @fac = Array.new(@max_n+1)
      @inv = Array.new(@max_n+1)
      @finv = Array.new(@max_n+1)

      @fac[0] = @fac[1] = 1
      @finv[0] = @finv[1] = 1
      @inv[1] = 1
      2.upto(@max_n) do |i|
          @fac[i] = @fac[i-1] * i % @mod
          @inv[i] = @mod - @inv[@mod%i] * (@mod/i) % @mod
          @finv[i] = @finv[i-1] * @inv[i] % @mod
      end
  end

  def nCk(n,k)
      @fac[n] * @finv[n - k] * @finv[k] % @mod
  end
end

x,y=gets.chomp.split.map(&:to_i)

if(y>x)
  tmp=y
  y=x
  x=tmp
end

if((2*x-y)%3!=0)
  puts 0
  exit
end

t=(2*x-y)/3;

if((x-t)%2!=0)
  puts 0
  exit
end

s=(x-t)/2;

combi = Combi.new(1000000)

puts combi.nCk(s+t,t)