For two integers $x$ and $y$ ($x,y\ge 2$), we will say that $x$ is a generator of $y$ if and only if $x$ can be transformed to $y$ by performing the following operation some number of times (possibly zero):

• Choose a divisor $d$ ($d\ge 2$) of $x$, then increase $x$ by $d$.

For example,

• $3$ is a generator of $8$ since we can perform the following operations: $3 \xrightarrow{d = 3} 6 \xrightarrow{d = 2} 8$;
• $4$ is a generator of $10$ since we can perform the following operations: $4 \xrightarrow{d = 4} 8 \xrightarrow{d = 2} 10$;
• $5$ is not a generator of $6$ since we cannot transform $5$ into $6$ with the operation above.

Now, Kevin gives you an array $a$ consisting of $n$ pairwise distinct integers ($a_i\ge 2$).

You have to find an integer $x\ge 2$ such that for each $1\le i\le n$, $x$ is a generator of $a_i$, or determine that such an integer does not exist.

Input

Each test contains multiple test cases. The first line of the input contains a single integer $t$ ($1\le t\le 10^4$) — the number of test cases. The description of test cases follows.

The first line of each test case contains a single integer $n$ ($1\le n\le 10^5$) — the length of the array $a$.

The second line contains $n$ integers $a_1,a_2,\ldots,a_n$ ($2\le a_i\le 4\cdot 10^5$) — the elements in the array $a$. It is guaranteed that the elements are pairwise distinct.

It is guaranteed that the sum of $n$ over all test cases does not exceed $10^5$.

Output

For each test case, output a single integer $x$ — the integer you found. Print $-1$ if there does not exist a valid $x$.

If there are multiple answers, you may output any of them.

见题面 Input 部分

见题面 Output 部分

In the first test case, for $x=2$:

• $2$ is a generator of $8$, since we can perform the following operations: $2 \xrightarrow{d = 2} 4 \xrightarrow{d = 4} 8$;
• $2$ is a generator of $9$, since we can perform the following operations: $2 \xrightarrow{d = 2} 4 \xrightarrow{d = 2} 6 \xrightarrow{d = 3} 9$.
• $2$ is a generator of $10$, since we can perform the following operations: $2 \xrightarrow{d = 2} 4 \xrightarrow{d = 2} 6 \xrightarrow{d = 2} 8 \xrightarrow{d = 2} 10$.

In the second test case, it can be proven that it is impossible to find a common generator of the four integers.