import java.io.*;
import java.util.*;

public class Solution {

    public static int perfect(long n){
        long sum=n+1;
        for(long i=2;i<=Math.sqrt(n);i++){
            if(n%i==0)
            sum+=i;
        }
        if(sum==n)
        return 1;
        else
        return 0;
    }
    public static void main(String[] args) {
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
        Scanner sc=new Scanner(System.in);
        long n=sc.nextLong();
        long sum=0;
        for(long i=1;i<=n;i++){
            if(perfect(i)==1){
                long sigma=2*n;
                double p=sigma/n;
                long k=(long)p;
                if(k-p==0.5)
                sum+=i;
            }
        }
        System.out.println(sum);
    }
}