B. Equal XORtime limit per test1 secondmemory limit per test256 megabytesinputstandard inputoutputstandard outputYou are given an array a of length 2n, consisting of each integer from 1 to n exactly twice.You are also given an integer k (1 \leq k \leq \lfloor \frac{n}{2} \rfloor ).You need to find two arrays l and r each of length \mathbf{2k} such that:   l is a subset^\dagger of [a_1, a_2, \ldots a_n]  r is a subset of [a_{n+1}, a_{n+2}, \ldots a_{2n}]  bitwise XOR of elements of l is equal to the bitwise XOR of elements of r; in other words, l_1 \oplus l_2 \oplus \ldots \oplus l_{2k} = r_1 \oplus r_2 \oplus \ldots \oplus r_{2k} It can be proved that at least one pair of l and r always exists. If there are multiple solutions, you may output any one of them.^\dagger A sequence x is a subset of a sequence y if x can be obtained by deleting several (possibly none or all) elements of y and rearranging the elements in any order. For example, [3,1,2,1], [1, 2, 3], [1, 1] and [3, 2] are subsets of [1, 1, 2, 3] but [4] and [2, 2] are not subsets of [1, 1, 2, 3].InputEach test contains multiple test cases. The first line contains a single integer t (1 \leq t \leq 5000) — the number of test cases. The description of the test cases follows.The first line of each test case contains 2 integers n and k (2 \le n \le 5 \cdot 10^4, 1 \leq k \leq \lfloor \frac{n}{2} \rfloor ).The second line contains 2n integers a_1, a_2, \ldots, a_{2n} (1 \le a_i \le n). It is guaranteed that every integer from 1 to n occurs exactly twice in a.It is guaranteed that the sum of n over all test cases does not exceed 5 \cdot 10^4.OutputFor each test case, output two lines. On the first line of output, output 2k integers l_1, l_2, \ldots, l_{2k}.On the second line of output, output 2k integers r_1, r_2, \ldots r_{2k}.If there are multiple solutions, you may output any one of them.ExampleInput
42 11 2 2 16 16 4 2 1 2 3 1 6 3 5 5 44 11 2 3 4 1 2 3 46 25 1 3 3 5 1 2 6 4 6 4 2Output
2 1
2 1
6 4
1 3
1 2
1 2
5 1 3 3
6 4 2 4
NoteIn the first test case, we choose l=[2,1] and r=[2,1]. [2, 1] is a subset of [a_1, a_2] and [2, 1] is a subset of [a_3, a_4], and 2 \oplus 1 = 2 \oplus 1 = 3.In the second test case, 6 \oplus 4 = 1 \oplus 3 = 2.
42 11 2 2 16 16 4 2 1 2 3 1 6 3 5 5 44 11 2 3 4 1 2 3 46 25 1 3 3 5 1 2 6 4 6 4 2
2 1 2 1 6 4 1 3 1 2 1 2 5 1 3 3 6 4 2 4 
['bitmasks', 'constructive algorithms', '*1100']