import java.util.*;

public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long n = sc.nextLong();
    long ans = 0;
    if((n % 2) == 0) {
      n /= 2;
    } else {
      
    }
    for(long i = 1; (i * i) <= n; i++) {
      if((n % i) == 0) {
        long t = n / i;
        ans += (i + t);
      }
    }
    System.out.println(ans);
  }
}