K = gets.to_i
prime = [2, 3, 5, 7, 11, 13]
synthesis = [4, 6, 8, 9, 10, 12]
count = 0

prime.each do |i|
  synthesis.each do |j|
    count += 1 if K == i * j
  end
end

puts count.to_f / (prime.length * synthesis.length)