$n = gets.chomp.to_i
$array = Array.new($n + 1, 0)

($n).times do |i|
  if i > 0
    $ii = i
    while $ii < $n
      $array[$ii] += 1
      $ii += i
    end
  end
end

$ans = 0
$array.each do |i|
  $ans += i
end
puts $ans 