(define n (string->number (read-line)))
(define k (string->number (read-line)))
(define (iterate0-n n)
  (let ((res (list 1)))
    (let loop ((i n) (p res))
      (if (< i 1)
        (cdr res)
        (begin
          (set-cdr! p (list (string->number (read-line))))
          (loop (- i 1) (cdr p)))))))

(define a (iterate0-n n))
(sort! a)
(define res (- (last a) (car a)))
(display res)
(newline)