N = gets.to_i

sum = N * (N - 1) / 2

ans = 0

1.upto(Math.sqrt(N).floor) {|i|
  if N % i == 0
    if sum % i == 0
      ans += i
      map[i] = 1
    end

    if sum % (N / i) == 0 and i != N / i
      ans += N / i
      map[N / i] = 1
    end
  end
}

puts ans