Introduction - If you have any usage issues, please Google them yourself
Fu major data structures and algorithms experimental questions 9.1 stones sean collected a lot of stones, which have many of the same, he wanted to know the collection of many different stones. Input behavior is a positive integer N (2 <N<=50000)表示收集的石头数。
接下来N行,每行1个正整数x代表一个编号为x的石头,两个石头相同当且仅当他们
的编号相同。
输出一行一个整数,表示不同的石头的个数。