(use scheme.vector)
(use gauche.collection)

(let* ((n (read)))
  (define vec (vector-map char->integer (string->vector (number->string n))))
  (print (apply max
		#?=(let loop ((is (iota (vector-length vec))))
		     (cond ((null? is) '())
			   (else
			    (let1 vec-copied (vector-copy vec)
				  (vector-swap! vec-copied 0 (car is))
				  (cons (string->number (list->string (map integer->char vec-copied)))
					(loop (cdr is))))))))))