def prime?(n)
    return false if n == 0 or n == 1
    res = true
    n.times do |i|
        next if i == 0 or i == 1
        if n % i == 0
            res = false
            break
        end
    end
    res
end

max = gets.chomp.to_i
res = []
(0..max).each do |i|
    res << i if prime?(i)
end

puts res.inject { |sum, k| sum + k}