text: import queue
  import util
  
  WINDOW_SIZE=25
  
  def solve(input_path):
    f = open(input_path)
    window_queue = queue.Queue()
    window_set = set()
    for _ in range(WINDOW_SIZE):
      n = next(util.next_int(f))
      window_queue.put(n)
      window_set.add(n)
  
    while (True):
      n = next(util.next_int(f))
      found = False
      for e in window_set:
        if n - e in window_set:
          found = True
          break
      if not found:
        return n
      o = window_queue.get()
      window_set.remove(o)
      window_queue.put(n)
      window_set.add(n)
  
  if __name__ == '__main__':
      print(solve('input.txt'))