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

(let (
      (N (read))
     )
  (let loop(
            (foo (read))
            (bar '())
           )
    (if (eof-object? foo)
        (let loop2(
                   (Min 0)
                   (i 0)
                   (baz (sort bar <))
                  )
          (if (and (< (list-ref baz i) (list-ref baz (+ i 1))) (or (= Min 0) (< (abs (- (list-ref baz i) (list-ref baz (+ i 1)))) Min)))
              (if (= (+ i 2) (length baz))
                  (System.out.println (abs (- (list-ref baz i) (list-ref baz (+ i 1)))))
                  (loop2 (abs (- (list-ref baz i) (list-ref baz (+ i 1)))) (+ i 1) baz)
              )
              (if (= (+ i 2) (length baz))
                  (System.out.println Min)
                  (loop2 Min (+ i 1) baz)
              )
          )
        )
        (loop (read) (cons foo bar))
    )
  )
)