using System;
using System.Collections.Generic;
using System.Linq;
using System.IO;
using System.Text;
using System.Numerics;

namespace Solver
{
    class Program
    {
        const int M = 1000000007;
        const double eps = 1e-9;
        static void Main()
        {
            var sw = new System.IO.StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false };
            var sc = new Scan();
            var n = sc.Long;
            if ((n & 1) == 1)
                sw.WriteLine(yaksum(n));
            else
                sw.WriteLine(yaksum(n / 2));

            sw.Flush();
        }
        static long yaksum(long n)
        {
            long sum = 0;
            for (long i = 1; i * i <= n; i++)
            {
                if (n % i > 0)
                    continue;

                sum += i;
                if (i * i < n)
                    sum += n / i;
            }
            return sum;
        }
    }
    class Scan
    {
        public int Int { get { return int.Parse(Console.ReadLine().Trim()); } }
        public long Long { get { return long.Parse(Console.ReadLine().Trim()); } }
        public string Str { get { return Console.ReadLine().Trim(); } }
        public int[] IntArr { get { return Console.ReadLine().Trim().Split().Select(int.Parse).ToArray(); } }
        public int[] IntArrWithSep(char sep) {  return Console.ReadLine().Trim().Split(sep).Select(int.Parse).ToArray(); }
        public long[] LongArr { get { return Console.ReadLine().Trim().Split().Select(long.Parse).ToArray(); } }
        public double[] DoubleArr { get { return Console.ReadLine().Split().Select(double.Parse).ToArray(); } }
        public string[] StrArr { get { return Console.ReadLine().Trim().Split(); } }
        public List<int> IntList { get { return Console.ReadLine().Trim().Split().Select(int.Parse).ToList(); } }
        public List<long> LongList { get { return Console.ReadLine().Trim().Split().Select(long.Parse).ToList(); } }
        public void Multi(out int a, out int b) { var arr = IntArr; a = arr[0]; b = arr[1]; }
        public void Multi(out int a, out int b, out int c) { var arr = IntArr; a = arr[0]; b = arr[1]; c = arr[2]; }
        public void Multi(out int a, out int b, out int c, out int d) { var arr = IntArr; a = arr[0]; b = arr[1]; c = arr[2]; d = arr[3]; }
        public void Multi(out int a, out string b) { var arr = StrArr; a = int.Parse(arr[0]); b = arr[1]; }
        public void Multi(out int a, out char b) { var arr = StrArr; a = int.Parse(arr[0]); b = arr[1][0]; }
        public void Multi(out long a, out long b) { var arr = LongArr; a = arr[0]; b = arr[1]; }
        public void Multi(out string a, out string b) { var arr = StrArr; a = arr[0]; b = arr[1]; }
    }
}