Read problems statements in Mandarin Chinese  and Russian. 

You have an array of integers A_{1}, A_{2}, ..., A_{N}. The function F(P), where P is a subset of A, is defined as the XOR (represented by the symbol ⊕) of all the integers present in the subset. If P is empty, then F(P)=0.

Given an integer K, what is the maximum value of K ⊕ F(P), over all possible subsets P of A?

------ Input ------ 

The first line contains T, the number of test cases. Each test case consists of N and K in one line, followed by the array A in the next line.

------ Output ------ 

For each test case, print the required answer in one line.

------ Constraints ------ 

$1 ≤ T ≤ 10$
$1 ≤ K, A_{i} ≤ 1000$
$Subtask 1 (30 points):1 ≤ N ≤ 20$
$Subtask 2 (70 points):1 ≤ N ≤ 1000$
 
----- Sample Input 1 ------ 
1
3 4
1 2 3
----- Sample Output 1 ------ 
7
----- explanation 1 ------ 

Considering all subsets:
F({}) = 0 ? 4 ? 0 = 4
F({1}) = 1 ? 4 ? 1 = 5
F({1,2}) = 3 ? 4 ? 3 = 7
F({1,3}) = 2 ? 4 ? 2 = 6
F({1,2,3}) = 0 ? 4 ? 0 = 4
F({2}) = 2 ? 4 ? 2 = 6
F({2,3}) = 1 ? 4 ? 1 = 5
F({3}) = 3 ? 4 ? 3 = 7
Therefore, the answer is 7.