require 'prime'
a = gets.to_i
count = 0
fps = (0..4).map { |n| 2**(2**n) + 1 }
(3..a).each do |n|
  count += 1 if Prime.prime_division(n).all? do |x|
    x[0] == 2 || (fps.include?(x[0]) && x[1] == 1)
  end
end
puts count