    x,y = gets.chomp.split(" ").map(&:to_i)
 
    a = (2 * y) - x
    b = (2 * x) - y
    
	MOD = (10 ** 9) + 7
 
    
    if a < 0 or b < 0 or a % 3 != 0 or b % 3 != 0
      puts 0
      exit
    end
      
    def kaijo(a, b)
      result = 1
      ([a,b].min..[a,b].max).each {|v| result = (result * v) % MOD}
      return result % MOD
    end
 
    def joho_gyakugen(a, b)
      #modを法とする逆元を計算
      result = 1
      ([a,b].min..[a,b].max).each {|v| result = (result * v) % MOD}
      return ruijo(result, MOD-2)
    end
    
    def ruijo(tei, bekisu)
      if bekisu == 0
        return 1
      elsif bekisu % 2 == 0
        result = ruijo((tei * tei) % MOD, bekisu / 2)
      else
        result = tei * ruijo((tei * tei) % MOD, bekisu / 2)
      end
      return result % MOD
    end
 
    n = [a, b].min / 3
    m = [a, b].max / 3
    total = n + m
    result = (kaijo(m+1, total) * joho_gyakugen(1, n))
    puts result % MOD