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

(let (
      (N (read))
     )
  (let loop(
            (foo (read))
            (bar '())
           )
    (if (not (eof-object? foo))
        (loop (read) (cons foo bar))
        (let loop2(
                   (i 0)
                   (Min 0)
                   (ls (sort bar <))
                  )
          (if (and (not (= (list-ref ls i) (list-ref ls (+ i 1))))
                   (or (< (abs (- (list-ref ls i) (list-ref ls (+ i 1)))) Min) (= Min 0)))
              (if (= i (- (length ls) 2))
                  (System.out.println (abs (- (list-ref ls i) (list-ref ls (+ i 1)))))
                  (loop2 (+ i 1) (abs (- (list-ref ls i) (list-ref ls (+ i 1)))) ls)
              )
              (if (= i (- (length ls) 2))
                  (System.out.println Min)
                  (loop2 (+ i 1) Min ls)
              )
          )
        )
    )
  )
)