class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            var divisors = from i in Enumerable.Range(1, n)
                           where n % i == 0
                           select i;
            int sum = 0;
            foreach (var divisor in divisors)
            {
                sum += divisor;
            }
            Console.WriteLine(sum);
        }
    }