(define (pass str)
  (list->string (map uplow (string->list str))))

(define (uplow char)
  (if (char=? char (char-upcase char)) ;charは大文字か？
      (char-downcase char)             ;大文字ならば小文字にして返す
      (char-upcase char)))             ;小文字ならば大文字にして返す

(define (main args)
  (print (pass (symbol->string (read)))) 0)