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.BufferedReader;
  import java.io.File;
  import java.io.FileNotFoundException;
  import java.io.FileWriter;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.math.BigInteger;
  
  import java.util.*;
  
  public class Main
  {
  
    
  
      public static void main(String[] args)
      {
          FastScanner input = new FastScanner();
         StringBuilder result = new StringBuilder();
          int tc = input.nextInt();
          while (tc-- > 0) {
            int n = input.nextInt();
        int a[] = new int[n];
        int b[] = new int[n];
          for (int i = 0; i < n; i++) {
              a[i] = input.nextInt();
              
          }
          if(n%2==0)
          {
              for (int i = 0; i <n; i+=2) {
                  b[i] = a[i+1];
                  b[i+1] = -a[i];
              }
          }
          else
          {
              
              for (int i = 0; i <n-3; i+=2) {
                  b[i] = a[i+1];
                  b[i+1] = -a[i];
              }
              int last1 = a[n-3];
              int last2 = a[n-2];
              int last3 = a[n-1];
              if(last1+last2!=0)
              {
                  b[n-3] = -last3;
                  b[n-2] = -last3;
                  b[n-1] = (last1+last2);
              }
              else if(last1+last3!=0)
              {
                  b[n-3] = -last2;
                  b[n-2] = (last1+last3);
                  b[n-1] = -last2;
              }
              else if(last2+last3!=0)
              {
                  b[n-3] =(last2+last3);
                  b[n-2] = -last1;
                  b[n-1] = -last1;
              }
          }
          for (int i : b) {
              result.append(i+" ");
          }
          result.append("\n");   
          }
          System.out.println(result);
          
        
      }
  
      static class FastScanner
      {
  
          BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
          StringTokenizer st = new StringTokenizer("");
  
          String next()
          {
              while (!st.hasMoreTokens()) {
                  try {
                      st = new StringTokenizer(br.readLine());
                  } catch (IOException e) {
                  }
              }
              return st.nextToken();
          }
  
          int nextInt()
          {
              return Integer.parseInt(next());
          }
  
          long nextLong()
          {
  
              return Long.parseLong(next());
          }
  
          double nextDouble()
          {
              return Double.parseDouble(next());
          }
  
          String nextLine() throws IOException
          {
              return br.readLine();
          }
      }
  
  }
  