The Little Elephant from the Zoo of Lviv has an array A that consists of N positive integers. Let A[i] be the i-th number in this array (i = 1, 2, ..., N).

Find the minimal number x > 1 such that x is a divisor of all integers from array A. More formally, this x should satisfy the following relations:

A[1] mod x = 0, A[2] mod x = 0, ..., A[N] mod x = 0,

where mod stands for the modulo operation. For example, 8 mod 3 = 2, 2 mod 2 = 0, 100 mod 5 = 0 and so on. If such number does not exist, output -1.

Input

The first line of the input contains a single integer T, the number of test cases. T test cases follow. The first line of each test case contains a single integer N, the size of the array A for the corresponding test case. The second line contains N space separated integers A[1], A[2], ..., A[N].

Output

For each test case output a single line containing the answer for the corresponding test case.

Constraints

1 ≤ T ≤ 100000
1 ≤ N ≤ 100000
The sum of values of N in each test file does not exceed 100000
1 ≤ A[i] ≤ 100000

Example

Input:
2
3
2 4 8
3
4 7 5

Output:
2
-1

Explanation

Case 1. Clearly 2 is a divisor of each of the numbers 2, 4 and 8. Since 2 is the least number greater than 1 then it is the answer.

Case 2. Let's perform check for several first values of x.

x
4 mod x
7 mod x
5 mod x

2
0
1
1

3
1
1
2

4
0
3
1

5
4
2
0

6
4
1
5

7
4
0
5

8
4
7
5

9
4
7
5

As we see each number up to 9 does not divide all of the numbers in the array. Clearly all larger numbers also will fail to do this. So there is no such number x > 1 and the answer is -1.

见题面

见题面