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.*;
  import java.math.*;
  
  public class Coder {
  
    static StringBuffer str=new StringBuffer();
    static int n;
    static long a[];
  
    static void solve(){
      long b[]=new long[n];
      int idx=2;
      if(n%2!=0){
        if((a[0]+a[1]) != 0){
          b[0]=-a[2];
          b[1]=-a[2];
          b[2]=a[0]+a[1];
        }else if((a[1]+a[2]) != 0){
          b[0]=a[1]+a[2];
          b[1]=-a[0];
          b[2]=-a[0];
        }else{
          b[0]=-a[1];
          b[1]=a[0]+a[2];
          b[2]=-a[1];
        }
        idx++;
      }else{
        b[0]=-a[1];
        b[1]=a[0];
      }
      for(int i=idx;i<n;i+=2){
        b[i]=-a[i+1];
        b[i+1]=a[i];
      }
      for(int i=0;i<n;i++) str.append(b[i]).append(" ");
      str.append("\n");
    }
  
    public static void main(String[] args) throws java.lang.Exception {
      BufferedReader bf;
      PrintWriter pw;
      boolean lenv=false;
      if(lenv){
        bf = new BufferedReader(
                            new FileReader("input.txt"));
        pw=new PrintWriter(new
              BufferedWriter(new FileWriter("output.txt")));
      }else{
        bf = new BufferedReader(new InputStreamReader(System.in));
        pw = new PrintWriter(new OutputStreamWriter(System.out));
      }
      int q = Integer.parseInt(bf.readLine().trim());
      while (q-- > 0) {
        n=Integer.parseInt(bf.readLine().trim());
        String s[]=bf.readLine().trim().split("\\s+");
        a=new long[n];
        for(int i=0;i<n;i++) a[i]=Long.parseLong(s[i]);
        solve();
      }
      pw.print(str);
      pw.flush();
      // System.out.print(str);
    }
  }