require 'set'

n = gets.chop.to_i

a = n - 1
b = n - 1
cnt = 0
memo = []

(1..a).each do |i|
    (1..b).each do |j|
        break if memo.include?(Set[i, j])
        if (i * j) < n
            #p "i:#{i} j:#{j}"
            cnt += 1
        else
            memo << Set[i, j]
            break
        end
    end
end

puts cnt