(let ((x (read)))
    (try (try (throw "cannot divide by zero")
     catch
     (lambda (exn)
       (cond ((= 0 (caddr x))
              (display exn)
              (newline)))
       (throw "No fractions allowed")))
         catch
         (lambda (exn)
           (cond ((not (integer? (/ (cadr x) (caddr x)))) (display exn)
                  (newline))
                 (else (display (/ (cadr x) (caddr x))))))))