Chef and Hamming Distance of arrays

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Read problems statements in Vietnamese
.Chef likes to work with arrays a lot. Today he has an array A of length N consisting of positive integers. Chef's little brother likes to follow his elder brother, so he thought of creating an array B of length N. The little brother is too small to think of new numbers himself, so he decided to use all the elements of array A to create the array B. In other words, array B is obtained by shuffling the elements of array A.
The little brother doesn't want Chef to know that he has copied the elements of his array A. Therefore, he wants to create the array B in such a way that the Hamming distance between the two arrays A and B is maximized. The Hamming distance between A and B is the number of indices i (1 ≤ i ≤ N) such that A_{i} ≠ B_{i}.
The brother needs your help in finding any such array B. Can you please find one such array for him?
Note that it's guaranteed that no element in A appears more than twice, i.e. frequency of each element is at most 2.
Input
 The first line of the input contains a single integer T denoting the number of test cases. The description of T test cases follows.
 The first line of each test case contains an integer N denoting the length of the array A.
 The second line contains N spaceseparated integers A_{1}, A_{2} ... A_{N}.
Output
 For each test case, print two lines.
 The first line should contain the maximum possible Hamming distance that array B can have from array A.
 The second line should contain N spaceseparated integers denoting the array B; the ith integer should denote the value of B_{i}. Note that B should be an array obtained after shuffling the elements of A.
Constraints
 1 ≤ T ≤ 10
 1 ≤ N ≤ 10^{5}
 1 ≤ A_{i} ≤ 10^{5}
 The frequency of each integer in the array A will be at most 2.
Subtasks
Subtask #1 (30 points): all elements in the array A are unique
Subtask #2 (30 points): 5 ≤ N ≤ 10^{5}
Subtask #3 (40 points): original constraints
Example
Input 3 2 1 2 3 1 2 1 4 2 6 5 2 Output 2 2 1 2 2 1 1 4 6 2 2 5
Author:  admin2 
Editorial  https://discuss.codechef.com/problems/CHEFHAM 
Tags  admin2, dec17 
Date Added:  1122017 
Time Limit:  3 sec 
Source Limit:  50000 Bytes 
Languages:  C, CPP14, JAVA, PYTH, PYTH 3.6, PYPY, CS2, PAS fpc, PAS gpc, RUBY, PHP, GO, NODEJS, HASK, rust, SCALA, swift, D, PERL, FORT, WSPC, ADA, CAML, ICK, BF, ASM, CLPS, PRLG, ICON, SCM qobi, PIKE, ST, NICE, LUA, BASH, NEM, LISP sbcl, LISP clisp, SCM guile, JS, ERL, TCL, kotlin, PERL6, TEXT, SCM chicken, PYP3, CLOJ, COB, FS 
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