require 'prime'

p, c = gets.split.map(&:to_i)
prime = Prime.each(13).to_a
composite = Array(2..13) - prime
sum = 0.0

prime.repeated_permutation(p).each do |x|
  composite.repeated_permutation(c).each do |y|
    sum += x.inject(1, :*) * y.inject(1, :*)
  end
end

puts sum / 6**(p + c)