require 'set'; require 'prime'; require 'pp'
INF=Float::INFINITY; MOD=10**9+7
n = gets.chomp.to_i

ans = 0
1.upto(1_000_000) do |a|
  1.upto(1_000_000) do |b|
    if a * b >= n
      break
    end
    ans += 1
  end
end

puts ans