Problem Description
Given an array with
n
integers, assume f(S) as the result of executing xor operation among all the elements of set S. e.g. if S={1,2,3} then f(S)=0.
your task is: calculate xor of all f(s), here s⊆S.
Input
This problem has multi test cases. First line contains a single integer T(T≤20) which represents the number of test cases.
For each test case, the first line contains a single integer number n(1≤n≤1,000) that represents the size of the given set. then the following line consists of n different integer numbers indicate elements(≤109) of the given set.
Output
For each test case, print a single integer as the answer.
Sample Input
1
3
1 2 3
Sample Output
0
In the sample，$S = {1, 2, 3}$, subsets of $S$ are: $\varnothing$, {1}, {2}, {3}, {1, 2}, {1, 3}, {2, 3}, {1, 2, 3}
