Given an array A. Find the highest unique element in array A. Unique element means that element should present only once in the array.

Input:

First line of input contains N, size of array A. Next line contains N space separated elements of array A.

Output:

Print highest unique number of array A. If there is no any such element present in array then print -1.

Constraints:

1 ≤ N ≤ 10⁶
0 ≤ A_i ≤ 10⁹