n = read_line.to_i
minimum_divisor = Array.new(n + 1) { |i| i }
2.upto(n // 2) do |i|
  2.upto(minimum_divisor[i]) do |p|
    break if i * p > n
    minimum_divisor[i * p] = p
  end
end
mu = Array.new(n + 1, 1)
2.upto(n) do |i|
  d = minimum_divisor[i]
  if i % (d.to_i64 * d) == 0
    mu[i] = 0
  else
    mu[i] = -1 * mu[i // d]
  end
end
puts mu.sum - 1