package no278;

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long n = sc.nextLong();
		long m = n % 2 == 0 ? n / 2 : n;
		long ans = 0;
		for(long i=1;i*i<=m;i++) {
			if (m % i == 0) {
				ans += i;
				if (i * i != m) {
					ans += m / i;
				}
			}
		}
		System.out.println(ans);
	}
	public static long gcd(long a,long b) {
		while(b!=0) {
			long r = a%b;
			a = b;
			b = r;
		}
		return a;
	}
}