Xiaoyue, Dongdong, and Archie have 7 extra-curricular books in total, and each of them has at least one. How many extracurricular books do Xiaoyue, Dongdong, and Archie have? Please write all possible situations.
小悦、冬冬、阿奇三个人一共有7本课外书，每个人至少有一本．小悦、冬冬、阿奇分别有几本课外书？请写出全部可能的情况．
<result>15</result>