import java.util.*;
public class Main {
	public static void myout(Object text){//standard output
		System.out.println(text);
	}
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		//String tmp = sc.next();
		//int tmp = sc.nextInt();
		//Long tmp = sc.nextLong();
		Long n = sc.nextLong();
		Long output = new Long(0);
		for(int i = 1; i <= n; i++){
		    if(n % i == 0){
		        output += i;
		    }
		}
		myout(output);
	}
}