def pn(n)
  c = 0
  i = 1
  while c < 3 && i <= n
    c += 1 if n % i == 0
    i += 1
  end
  return n if c == 2
end
def pna(n)
  a = []
  n.times do |i|
    a << i+1 if pn(i+1) != nil
  end
  return a
end
p pna(gets.to_i).sum