(defvar n (read)) 

(defvar c (apply #'vector (sort (loop repeat n
                                      collect (read)) #'<))) 

(defvar s (loop for i from 0 to (1- (floor n 2))
                sum (aref c i))) 
(defvar b (loop for i from (ceiling n 2) to (1- n)
                sum (aref c i))) 

(princ (if (evenp n)
           (abs (- (abs s) (abs b))) 
           (max (abs (- (abs (+ s (aref c (floor n 2)))) (abs b)))
                (abs (- (abs (+ b (aref c (floor n 2)))) (abs s)))))) 
(fresh-line)