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.util.*;
  import java.io.BufferedReader;
  
  import java.io.InputStreamReader;
  import java.util.StringTokenizer;
  import java.io.IOException;
  public class solution {
  
  public static void main(String[] args)  {
  	Scanner sc=new Scanner(System.in);
  	int t=sc.nextInt();
  	while(t-->0) {
  	int n=sc.nextInt();
  	int arr[]=new int[n];
  	for(int i=0;i<n;i++)
  		arr[i]=sc.nextInt();
  	if(n%2!=0)
  		n=n-3;
  	for(int i=0;i<n;i+=2)
  	{	
  		
  		System.out.print(arr[i+1]+" "+(-arr[i])+" ");
  	}
  	
  	if(arr.length-n==3 )
  	{
  	    if(arr[n]+arr[n+1]!=0 )
  	    	System.out.print(arr[n+2]+" "+arr[n+2]+" "+(-arr[n]-arr[n+1]) );
  	    else if(arr[n+2]+arr[n+1]!=0 )
  	    	System.out.print((-arr[n+2]-arr[n+1])+" "+ arr[n]+" "+arr[n] );
  	    else
  	    	System.out.print(arr[n+1]+" "+ (-arr[n+2]-arr[n])+" "+arr[n+1] );
  	}
  		
  	System.out.println();
      }
      }
      }
  
  