A travel agency travels to Xiamen with a total of 23 people. All of them stay in 2-person rooms and 3-person rooms in the hotel. In order to save costs, there are no free beds. How many ways does this tour group have?
旅行社一个赴厦门旅游团共23人，全部入住酒店的2人间和3人间，为了节约费用，不能有空床位，那么这个旅游团一共有多少种入住的方法．
<result>4</result>