题目描述

An AVL tree is a self-balancing binary search tree.  In an AVL tree, the heights of the two child subtrees of any node differ by at most one; if at any time they differ by more than one, rebalancing is done to restore this property.  Figures 1-4 illustrate the rotation rules.

    


    

Now given a sequence of insertions, you are supposed to tell the root of the resulting AVL tree.

输入描述:

Each input file contains one test case.  For each case, the first line contains a positive integer N (<=20) which is the total number of keys to be inserted.  Then N distinct integer keys are given in the next line.  All the numbers in a line are separated by a space.

输出描述:

For each test case, print ythe root of the resulting AVL tree in one line.

输入例子:

5
88 70 61 96 120

输出例子:

70