(define (divisor n)
  (let loop ([i 1]
             [l '()])
    (cond [(> (* i i) n) l]
          [(zero? (remainder n i)) (if (= i (quotient n i))
                                       (loop (+ i 1) (cons i l))
                                       (loop (+ i 1) (cons i (cons (quotient n i) l))))]
          [else (loop (+ i 1) l)])))

(define (solve n)
  (apply + (divisor n)))

(define (main args)
  (let ([n (read)])
    (print (solve n)))
  0)