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.lang.*;
  import java.io.*;
  public class MyAnswer {
       public static void main(String[] args)throws IOException{
            FastScanner scan = new FastScanner();
            //SuperFastScanner scan = new SuperFastScanner();
            PrintWriter out = new PrintWriter(System.out);
            StringBuilder result = new StringBuilder();
       
            int t = scan.nextInt();
            while (t-- > 0){
                 int n = scan.nextInt();
                 int arr[] = scan.nextIntArray(n);
                 if(n%2==0){
                      int j = n/2;
                      for(int i = j;i<n;i++){
                           int val = arr[i] * -1;
                           result.append(val + " ");
                      }
                      for(int i = 0;i<j;i++){
                           int val = arr[i] ;
                           result.append(val + " ");
                      }
                 }else{
                      int j = (n-3)/2;
                      for(int i = j;i<n-3;i++){
                           int val = arr[i] * -1;
                           result.append(val + " ");
                      }
                      for(int i = 0;i<j;i++){
                           int val = arr[i] ;
                           result.append(val + " ");
                      }
                      
                      if(arr[n-3]+arr[n-2] !=0 ){
                           int sum = arr[n-3] + arr[n-2];
                           sum *=-1;
                           result.append(arr[n-1] + " ");
                           result.append(arr[n-1] + " ");
                           result.append(sum+ " ");
                           
                      }else if(arr[n-1]+arr[n-2] !=0 ){
                           int sum = arr[n-1] + arr[n-2];
                           sum *=-1;
                           result.append(sum+ " ");
                           result.append(arr[n-3] + " ");
                           result.append(arr[n-3]+" ");
                           
                      }else{
                           int sum = arr[n-1] + arr[n-3];
                           sum *=-1;
                           result.append(arr[n-2] + " ");
                           result.append(sum+ " ");
                           result.append(arr[n-2]+ " ");
                      }
                           
                 }
                 result.append("\n");
                 
            }
            out.println(result);
            out.flush();
       }
       public static int solve(String str,char ch){
            int ans = 0;
            int l = str.length();
            int i = 0,j = l-1;
            while(i<=j){
                 char a = str.charAt(i);
                 char b = str.charAt(j);
                 if(a==b){
                      i++;
                      j--;
                 }else{
                      if(a==ch){
                           i++;
                           ans++;
                      }else if(b==ch){
                           j--;
                           ans++;
                      }else{
                           return 10000000;
                      }
                 }
            }
            return ans;
       }
  
       static class FastScanner{ //10^5 -- .15 sec && 4*10^6 ---> .86 sec
  
            BufferedReader br;
            StringTokenizer st;
            
            public FastScanner(){
                 br = new BufferedReader(new InputStreamReader(System.in));
            }
            public 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());
            }
            public long nextLong(){
                 return Long.parseLong(next());
            }
            public double nextDouble(){
                 return Double.parseDouble(next());
            }
            public String nextLine(){
                 String str = "";
                 try{
                      str = br.readLine();
                 }catch (IOException e){
                      e.printStackTrace();
                 }
                 return str;
            }
            public int[] nextIntArray(int n){
                 int arr[] = new int[n];
                 for(int i = 0;i<n;i++){
                      arr[i] = nextInt();
                 }
                 return arr;
            }
            public long[] nextLongArray(int n){
                 long arr[] = new long[n];
                 for(int i = 0;i<n;i++){
                      arr[i] = nextLong();
                 }
                 return arr;
            }
            public double[] nextDoubleArray(int n){
                 double arr[] = new double[n];
                 for(int i = 0;i<n;i++){
                      arr[i] = nextDouble();
                 }
                 return arr;
            }
            public String[] nextStringArray(int n){
                 String arr[] = new String[n];
                 for(int i = 0;i<n;i++){
                      arr[i] = next();
                 }
                 return arr;
            }
      }
       
  
  }
  