队列可以在队列的两端进行插入和删除操作，既可在队尾进行插入/删除，又可在队头进行插入/删除。现有11个不同的元素顺序输入到队列，那么可以得到多少种不同的排列？Deque can do insert and delete operations on both ends of the queue, can insert / delete in the team head and also in the tail. Existing 11 different elements enter the double-ended queue orderly, then how many different permutations can you get?