description: Vupsen and Pupsen were gifted an integer array. Since Vupsen doesn't like the number 0, he threw away all numbers equal to 0 from the array. As a result, he got an array a of length n.
  
  Pupsen, on the contrary, likes the number 0 and he got upset when he saw the array without zeroes. To cheer Pupsen up, Vupsen decided to come up with another array b of length n such that ∑_{i=1}^{n}a_i ⋅ b_i=0. Since Vupsen doesn't like number 0, the array b must not contain numbers equal to 0. Also, the numbers in that array must not be huge, so the sum of their absolute values cannot exceed 10^9. Please help Vupsen to find any such array b!
  
  Input
  
  The first line contains a single integer t (1 ≤ t ≤ 100) — the number of test cases. The next 2 ⋅ t lines contain the description of test cases. The description of each test case consists of two lines.
  
  The first line of each test case contains a single integer n (2 ≤ n ≤ 10^5) — the length of the array.
  
  The second line contains n integers a_1, a_2, …, a_n (-10^4 ≤ a_i ≤ 10^4, a_i ≠ 0) — the elements of the array a.
  
  It is guaranteed that the sum of n over all test cases does not exceed 2 ⋅ 10^5.
  
  Output
  
  For each test case print n integers b_1, b_2, …, b_n — elements of the array b (|b_1|+|b_2|+… +|b_n| ≤ 10^9, b_i ≠ 0, ∑_{i=1}^{n}a_i ⋅ b_i=0).
  
  It can be shown that the answer always exists.
  
  Example
  
  Input
  
  
  3
  2
  5 5
  5
  5 -2 10 -9 4
  7
  1 2 3 4 5 6 7
  
  
  Output
  
  
  1 -1
  -1 5 1 -1 -1
  -10 2 2 -3 5 -1 -1
  
  Note
  
  In the first test case, 5 ⋅ 1 + 5 ⋅ (-1)=5-5=0. You could also print 3 -3, for example, since 5 ⋅ 3 + 5 ⋅ (-3)=15-15=0
  
  In the second test case, 5 ⋅ (-1) + (-2) ⋅ 5 + 10 ⋅ 1 + (-9) ⋅ (-1) + 4 ⋅ (-1)=-5-10+10+9-4=0.
solution: import java.awt.*;
  import java.io.*;
  import java.util.*;
  
  public class Main {
  	static BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
  	static StringBuilder str = new StringBuilder();
  	
  	public static void main(String[] args) throws NumberFormatException, IOException {
  		int t = Integer.parseInt(reader.readLine());
  		while (t-- > 0) {
  			solve();
  		}
  		printRes();
  	}
  	
  	public static void printRes() {
  		
  		System.out.println(str);
  	}
  
  	public static void solve() throws IOException {
  		int n = Integer.parseInt(reader.readLine());
  		String[] s = reader.readLine().split(" ");
  		int[] nums = new int[n];
  		
  		for (int i = 0; i < n; i++) {
  			nums[i] = Integer.parseInt(s[i]);
  		}
  		
  		int i = 0;
  		
  		if (n % 2 == 1) {
  			if (nums[1] + nums[2] != 0) {
  				str.append(-(nums[1] + nums[2]) + " " + nums[0] + " " + nums[0] + " ");
  			} else if (nums[0] + nums[2] != 0) {
  				str.append(nums[1] + " " + -(nums[0] + nums[2]) + " " + nums[1] + " ");
  			} else {
  				str.append(nums[2] + " " + nums[2] + " " + -(nums[0] + nums[1]) + " ");
  			}
  			i = 3;
  		}
  		for (; i < n; i+=2) {
  			if (nums[i] > 0 && nums[i+1] > 0) {
  				str.append(nums[i+1] + " " + (-nums[i]) + " ");
  			} else if (nums[i] < 0 && nums[i+1] < 0) {
  				str.append(nums[i+1] + " " + Math.abs(nums[i]) + " ");
  			} else {
  				str.append(Math.abs(nums[i+1]) + " " + Math.abs(nums[i]) + " ");
  			}
  		}
  		str.append("\n");
  	}
  }
  