N = gets.to_i

sum = (1 + (N - 1)) * (N - 1) / 2

ans = 0

map = {}

1.upto(Math.sqrt(N).floor) {|i|
  if N % i == 0 and sum % i == 0
    if not map.include?(i)
      ans += i
      map[i] = 1
    end
    if (not map.include?(N / i)) and sum % (N / i) == 0
      ans += (N / i)
      map[N / i] = 1
    end
  end
}

puts ans