时间限制：1秒 内存限制：256兆 题目描述
Given a set of n integers: A = {a1, a2,..., an}, calculate the second max integer in the set.
输入格式
The first line is an integer n (2<=n<=5000). The second line contains n integers: a1, a2, ..., an. (|ai| <= 10000).
输出格式
The second max integer in the set.