(define (read-list n)
  (cond [(zero? n) '()]
        [else (let1 x (read-line)
                    (cons x (read-list (- n 1))))]))

(define (solve ls)
  (apply string-append ls))

(define (main args)
  (let* ([n (string->number (read-line))]
         [ls (read-list n)])
    (print (solve ls)))
  0)