The Potion Shelf

Mira the Witch keeps potions on a shelf, each with a power level. She needs the second most powerful potion (second largest DISTINCT value) as a backup. If no second distinct value exists, output NO BACKUP.

Your Task

Given ~N~ integers (potion power levels), find the second largest distinct value. If none exists, output NO BACKUP.

Input Specification

The first line contains ~T~ — the number of shelves. Each shelf starts with ~N~ on its own line, followed by ~N~ space-separated integers.

Output Specification

For each shelf print the second largest distinct value, or NO BACKUP.

Sample Input

2
5
5 3 9 7 9
3
4 4 4

Sample Output

7
NO BACKUP

Constraints

~1 \le T \le 100\,000~
~2 \le N \le 10\,000~
~1 \le each value \le 100\,0000~

Test cases available here!