"Readers can pick up this book and become familiar with C++ in a short time. Stan has taken a very broad and complicated topic and reduced it to the essentials that budding C++ programmers need to know to write real programs. His case study is effective and provides a familiar thread throughout the book.
給定兩個集合A、B，集合內的任一元素x滿足1 ≤ x ≤ 109，并且每個集合的元素個數不大于105。我們希望求出A、B之間的關系。
任 務 ：給定兩個集合的描述，判斷它們滿足下列關系的哪一種：
A是B的一個真子集，輸出“A is a proper subset of B”
B是A的一個真子集，輸出“B is a proper subset of A”
A和B是同一個集合，輸出“A equals B”
A和B的交集為空，輸出“A and B are disjoint”
上述情況都不是，輸出“I m confused!”
