(define (System.out.println x)
  (begin
    (display x)
    (newline)
  )
)

(let (
      (S (string->list (symbol->string (read))))
     )
  (let loop(
            (i 0)
            (Result '())
            )
    (if (char-upper-case? (list-ref S i))
        (if (= i (- (length S) 1))
            (System.out.println (list->string (reverse (cons (char-downcase (list-ref S i)) Result))))
            (loop (+ i 1) (cons (char-downcase (list-ref S i)) Result))
        )
        (if (= i (- (length S) 1))
            (System.out.println (list->string (reverse (cons (char-upcase (list-ref S i)) Result))))
            (loop (+ i 1) (cons (char-upcase (list-ref S i)) Result))
        )
    )
  )
)