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 q4 {
      public static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
  
      public static class Pair{
          long val;
          int i;
  
          Pair(long val,int i){
              this.val = val;
              this.i = i;
          }
      }
      public static void solve() throws Exception {
          String[] parts = br.readLine().split(" ");
          int n = Integer.parseInt(parts[0]);
  
          Pair[] arr = new Pair[n];
  
          parts = br.readLine().split(" ");
          for (int i = 0; i < n; i++) {
              arr[i] = new Pair(Long.parseLong(parts[i]),i);
          }
  
          long[] ans = new long[n];
  
          if(n % 2 == 0){
              for(int i = 0;i < n;i += 2){
                  ans[i] = -arr[i + 1].val;
                  ans[i + 1] = arr[i].val;
              }
          }else{
              Arrays.sort(arr,(a,b) ->{
                  return Math.abs((int)a.val) - Math.abs((int)b.val);
              });
  
              ans[arr[0].i] = Math.abs(arr[1].val) + Math.abs(arr[2].val);
  
              if(arr[0].val < 0) {
                  if(arr[1].val < 0) ans[arr[1].i] = -Math.abs(arr[0].val);
                  else ans[arr[1].i] = Math.abs(arr[0].val);
              }else {
                  if(arr[1].val < 0) ans[arr[1].i] = Math.abs(arr[0].val);
                  else ans[arr[1].i] = -Math.abs(arr[0].val);
              }
  
              if(arr[0].val < 0) {
                  if(arr[2].val < 0) ans[arr[2].i] = -Math.abs(arr[0].val);
                  else ans[arr[2].i] = Math.abs(arr[0].val);
              }else {
                  if(arr[2].val < 0) ans[arr[2].i] = Math.abs(arr[0].val);
                  else ans[arr[2].i] = -Math.abs(arr[0].val);
              }
              for(int i = 3;i < n;i += 2){
                  long v1 = Math.abs(arr[i].val),v2 = Math.abs(arr[i + 1].val);
  
                  if(v2 % v1 == 0){
                      ans[arr[i].i] = v2 / v1;
  
                      if(arr[i].val < 0) {
                          if(arr[i + 1].val < 0) ans[arr[i + 1].i] = -1;
                          else ans[arr[i + 1].i] = 1;
                      }else {
                          if(arr[i + 1].val < 0) ans[arr[i + 1].i] = 1;
                          else ans[arr[i + 1].i] = -1;
                      }
                  }else{
                      ans[arr[i].i] = -arr[i + 1].val;
                      ans[arr[i + 1].i] = arr[i].val;
                  }
              }
          }
          
          for(long val : ans) System.out.print(val + " ");
          System.out.println();
      }
  
      public static void main(String[] args) throws Exception {
  
          int tests = Integer.parseInt(br.readLine());
          for (int test = 1; test <= tests; test++) {
              solve();
          }
      }
  }
  