2697

(define (div a b)
  (if (>= (* a b) 0)
      (floor (/ a b))
      (+ (floor (/ a b)) 1)))
(define (gcd a b)
  (define (make-ret-val n-val)
    (list (car n-val)
          (- (caddr n-val)
             (* (div b a) (cadr n-val)))
          (cadr n-val)))
  (if (= a 0)
      (list b 0 1)
      (make-ret-val (gcd (remainder b a) a))))
(define (diof-solve a b c)
  (define (make-ret-val n-val)
    (if (= 0 (remainder c (car n-val)))
        (list #t (floor (/ (* (cadr n-val) c) (car n-val)))
            (floor (/ (* (caddr n-val) c) (car n-val)))
            (car n-val))
        (list #f 0 0 0)))
  (cond ((and (= a 0) (= b 0))
         (if (= c 0)
             (list #t 0 0 0)
             (list #f 0 0 0)))
        ((= a 0)
         (if (= 0 (remainder c b))
             (list #t 0 (floor (/ c b)) 0)
             (list #f 0 0 0)))
        ((= b 0)
         (if (= 0 (remainder c a))
             (list #t (floor (/ c a)) 0 0)
             (list #f 0 0 0)))
        (else (make-ret-val (gcd a b)))))
(define (solve-task rx ry a b)
  (define (solve-task-subproc sol)
    (define (make-kl)
      (if (not (= 0 (remainder (* (cadr sol) (cadddr sol)) b)))
          (+ (floor (/ (* (- (cadr sol)) (cadddr sol)) b)) 1)
          (floor (/ (* (- (cadr sol)) (cadddr sol)) b))))
    (define (make-kh)
      (if (not (= 0 (remainder (* (caddr sol) (cadddr sol)) a)))
          (+ (floor (/ (* (caddr sol) (cadddr sol)) a)) 1)
          (floor (/ (* (caddr sol) (cadddr sol)) a))))
    (define (solve-task-subsubproc kl kh)
      (define (sub-sub-sub kkl kkh)
        (cond
         ((= kkl -2000000000)
          (+ (cadr sol) (floor (/ (* kkh b) (cadddr sol)))
             (- (caddr sol)) (floor (/ (* kkh a) (cadddr sol)))))
         ((= kkh 2000000000)
          (+ (cadr sol) (floor (/ (* kkl b) (cadddr sol)))
             (- (caddr sol)) (floor (/ (* kkl a) (cadddr sol)))))
         (else (min
                (+ (cadr sol) (floor (/ (* kkh b) (cadddr sol)))
                   (- (caddr sol)) (floor (/ (* kkh a) (cadddr sol))))
                (+ (cadr sol) (floor (/ (* kkl b) (cadddr sol)))
                   (- (caddr sol)) (floor (/ (* kkl a) (cadddr sol))))))))
      (sub-sub-sub (max (if (> (* b (cadddr sol)) 0) kl -2000000000)
                        (if (> (* a (cadddr sol)) 0) kh -2000000000))
                   (min (if (< (* b (cadddr sol)) 0) kl 2000000000)
                        (if (< (* a (cadddr sol)) 0) kh 2000000000))))
    (cond ((not (car sol)) -1)
          ((= a 0)
           (max -1 (- (caddr sol))))
          ((= b 0)
           (max -1 (cadr sol)))
          (else
           (solve-task-subsubproc (make-kl) (make-kh)))))
  (max -1 (solve-task-subproc (diof-solve a b (- ry rx)))))
(display (solve-task (read) (read) (read) (read)))
(display (newline))