Problem A. Second Best ≡

Input file:input.txt   Time limit:2 sec
Output file:output.txt   Memory limit:256 Mb

Statement

Given the sequence of integers A1, A2, …, AN, find a number As such that there exists exactly one Am > As, and for all k ≠ m Ak ≤ As.

Input file format

Input contains N followed by A1 A2… AN.

Output file format

Output should contain a single integer — As, or  − 1 if no such number exists.

Constraints

1 ≤ N ≤ 1000000, 0 ≤ Ai ≤ 109,

Sample tests

No. Input file (input.txt) Output file (output.txt)
1 
3
1 2 3
 
2
2 
4
3 3 2 3
 
-1
0.125s 0.015s 15