(defun has-duplicate-char (s)
  (let ((char-set (make-hash-table :test 'equal)))
    (loop for char across s do
      (if (gethash char char-set)
          (return-from has-duplicate-char t)
          (setf (gethash char char-set) t)))
    nil))

(defun main ()
  (let ((n (read))
        (s (read-line)))
    (declare (ignore n))
    (if (has-duplicate-char s)
        (format t "Yes~%")
        (format t "No~%"))))

(main)