require 'prime'

N = gets.to_i
ans = 0

if N == 2
  puts 1
  exit
end

Prime.each(N) do |r|
  q = r ** 2 - 2

  next if N < q

  if q.prime?
    if r == q
      ans += 1
    else
      ans += 2
    end
  end
end

puts ans