Virtual contest is a way to take part in past contest, as close as possible to participation on time. It is supported only ICPC mode for virtual contests.
If you've seen these problems, a virtual contest is not for you - solve these problems in the archive.
If you just want to solve some problem from a contest, a virtual contest is not for you - solve this problem in the archive.
Never use someone else's code, read the tutorials or communicate with other person during a virtual contest.

No tag edit access

B. Johnny and His Hobbies

time limit per test

1 secondmemory limit per test

256 megabytesinput

standard inputoutput

standard outputAmong Johnny's numerous hobbies, there are two seemingly harmless ones: applying bitwise operations and sneaking into his dad's office. As it is usually the case with small children, Johnny is unaware that combining these two activities can get him in a lot of trouble.

There is a set $$$S$$$ containing very important numbers on his dad's desk. The minute Johnny heard about it, he decided that it's a good idea to choose a positive integer $$$k$$$ and replace each element $$$s$$$ of the set $$$S$$$ with $$$s \oplus k$$$ ($$$\oplus$$$ denotes the exclusive or operation).

Help him choose such $$$k$$$ that Johnny's dad will not see any difference after his son is done playing (i.e. Johnny will get the same set as before playing). It is possible that no such number exists. It is also possible that there are many of them. In such a case, output the smallest one. Note that the order of elements in a set doesn't matter, i.e. set $$$\{1, 2, 3\}$$$ equals to set $$$\{2, 1, 3\}$$$.

Formally, find the smallest positive integer $$$k$$$ such that $$$\{s \oplus k | s \in S\} = S$$$ or report that there is no such number.

For example, if $$$S = \{1, 3, 4\}$$$ and $$$k = 2$$$, new set will be equal to $$$\{3, 1, 6\}$$$. If $$$S = \{0, 1, 2, 3\}$$$ and $$$k = 1$$$, after playing set will stay the same.

Input

In the first line of input, there is a single integer $$$t$$$ ($$$1 \leq t \leq 1024$$$), the number of test cases. In the next lines, $$$t$$$ test cases follow. Each of them consists of two lines.

In the first line there is a single integer $$$n$$$ ($$$1 \leq n \leq 1024$$$) denoting the number of elements in set $$$S$$$. Second line consists of $$$n$$$ distinct integers $$$s_i$$$ ($$$0 \leq s_i < 1024$$$), elements of $$$S$$$.

It is guaranteed that the sum of $$$n$$$ over all test cases will not exceed $$$1024$$$.

Output

Print $$$t$$$ lines; $$$i$$$-th line should contain the answer to the $$$i$$$-th test case, the minimal positive integer $$$k$$$ satisfying the conditions or $$$-1$$$ if no such $$$k$$$ exists.

Example

Input

6 4 1 0 2 3 6 10 7 14 8 3 12 2 0 2 3 1 2 3 6 1 4 6 10 11 12 2 0 1023

Output

1 4 2 -1 -1 1023

Note

In the first test case, the answer is $$$1$$$ because it is a minimum positive integer and it satisfies all the conditions.

Codeforces (c) Copyright 2010-2020 Mike Mirzayanov

The only programming contests Web 2.0 platform

Server time: Aug/14/2020 12:22:04 (h1).

Desktop version, switch to mobile version.

Supported by

User lists

Name |
---|