import java.util.Scanner;


public class Main_yukicoder278_1 {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        long n = sc.nextLong();

        if (n == 1) {
        } else if (n % 2 == 1) {
        } else {
        	n = n / 2;
        }

        if (n != 1) {
        	long ret = 0;
        	for (long j = 1; j * j <= n; j++) {
        		if (n % j == 0) {
        			ret += j;
        			if (j != n / j) {
        				ret += n / j;
        			}
        		}
        	}
		
        	System.out.println(ret);
        } else {
        	System.out.println("1");
        }
		
		sc.close();
    }
}