require 'prime'

class Integer
  def divisor_count
    return 1 if self == 1
    Prime.prime_division(self).reduce(1) {|m, d| m *= d[1] + 1}
  end
end

n = gets.to_i

count = 0
for i in 1..n-1 do
  count += i.divisor_count
end

puts count