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.io.*;
  import java.util.*;
  
  public class new1{
      static int gcd(int a, int b)
      {
        if (b == 0)
          return a;
        return gcd(b, a % b);
      }
       
  
  	public static void main(String[] args)  throws IOException{
      	FastReader s = new FastReader();
      	BufferedWriter output = new BufferedWriter(new OutputStreamWriter(System.out));
      	int t =  s.nextInt();
      	for(int z = 0; z < t; z++) {
      		int n = s.nextInt();
      		long[] arr = new long[n];
      		for(int i = 0; i < n; i++) {
      			arr[i] = s.nextLong();
      		}
      		if(n % 2 == 0) {
      			for(int i = 0; i < n; i = i + 2) {
      				System.out.print((- arr[i + 1]) + " " + arr[i] + " ");
      			}
      		}
      		else {
      			if(arr[1] + arr[2] != 0)System.out.print((arr[1] + arr[2]) + " " + (-arr[0]) + " " + (-arr[0]) + " ");
      			else System.out.print((arr[1] - arr[2]) + " " + (-arr[0]) + " " + (arr[0]) + " ");
      			for(int i = 3; i < n; i = i + 2) {
      				System.out.print((- arr[i + 1]) + " " + arr[i] + " ");
      			}
      		}
      		
      		System.out.println();
      		
      		
      		
      		
      	}
      			//output.flush();	
      }
  }
  
  class FastReader {
      BufferedReader br;
      StringTokenizer st;
      public FastReader() {
          br = new BufferedReader(new InputStreamReader(System.in));
      }
      String next() {
          while (st == null || !st.hasMoreElements()) {
              try {
                  st = new StringTokenizer(br.readLine());
              } catch (IOException e) {
                  e.printStackTrace();
              }
          }
          return st.nextToken();
      }
   
      public int nextInt() {
          return Integer.parseInt(next());
      }
   
      long nextLong() {
          return Long.parseLong(next());
      }
   
      double nextDouble() {
          return Double.parseDouble(next());
      }
   
      String nextLine() {
          String str = "";
          try {
              str = br.readLine();
          } catch (IOException e) {
              e.printStackTrace();
          }
          return str;
  }}