N=gets.to_i
n1 = N - 1
n2 = n1
res = 0
ans = []
tmp = 0
[*1..n1].each do |a|
  [*1..n2].each do |b|
    tmp = b
    #p "#{a} #{b}"
    if a * b <= (N - 1)
      res += 1
      #ans << [a, b]
    else
      break
    end
  end
  n2 = tmp
end
p res
#abc = (N-1) * 2 # [*1..[*1..N-1].size].size
#p abc
#p ([*1..N-1].sum * 2) + (N / 2 - 1) + 1
=begin
res = 0
ans = []
ab=[*1..(N-1)].repeated_permutation(2).to_a

ab.each do |a, b|
  if a * b <= (N - 1)
    res += 1
    ans << [a, b]
  end
end
=end
#p ans
#p res