import java.math.BigInteger;
import java.util.Arrays;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.Scanner;
import java.util.Set;

public class Main {

	public static long gcd(long a, long b){
		return b == 0 ? a : gcd(b, a % b);
	}
	
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		final long N = sc.nextLong();
		
		final long max = N % 2 != 0 ? N : N - 1;
		//System.out.println(max);
		final long sqrt = (long)(Math.floor(Math.sqrt(max)));
		
		long answer = 0;
		for(long div_fst = 1; div_fst <= sqrt; div_fst++){
			if(max % div_fst != 0) { continue; }
			
			final long div_snd = max / div_fst;
			if(div_fst > div_snd){ break; }
			//System.out.println(div_fst + " " + div_snd);
			
			answer += div_fst;
			if(div_fst < div_snd){
				answer += div_snd;
			}
		}
		
		System.out.println(answer);
		
	}

}