n = gets.strip.to_i
count = 0
(1..n - 1).each do |a|
  max_b = (n - 1) / a
  (a..max_b).each do |b|
    if n > a * b
      if a == b
        count += 1
      else
        count += 2
      end
    end
  end
end

puts count
