(defun max-counters (n a)
  (let ((counters (make-array n :initial-element 0))
        (max-counter 0)
        (last-update 0)
        (condition (1+ n)))
    (dolist (v a)
      (when (<= v n)
        (let ((index (1- v)))
          (when (< (aref counters index) last-update)
            (setf (aref counters index) last-update))
          (incf (aref counters index))
          (setf max-counter (max max-counter (aref counters index)))))
      (when (= v condition)
        (setf last-update max-counter)))
    (dotimes (k n)
      (when (< (aref counters k) last-update)
        (setf (aref counters k) last-update)))
    (coerce counters 'list)))