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.BufferedWriter;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.io.OutputStreamWriter;
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.Collections;
  import java.util.Deque;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.LinkedList;
  import java.util.List;
  import java.util.Map;
  import java.util.PriorityQueue;
  import java.util.Queue;
  import java.util.Set;
  import java.util.stream.Stream;
  
  public class CasimirString {
  	
  	static BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
  	static BufferedWriter out = new BufferedWriter(new OutputStreamWriter(System.out));
  
  	
  	public static void main(String[] args) throws NumberFormatException, IOException {
  		// TODO Auto-generated method stub
  
  		int cases = Integer.parseInt(reader.readLine());
      	
      	while(cases-- > 0) {
      		
      		String[] firstLine = reader.readLine().split(" ");
      		int n = Integer.parseInt(firstLine[0]);
      		
      		Integer[] arr = convertToIntArray(reader.readLine().split(" "));
      		List<Integer> ans = new ArrayList<>();
      		
      		if(arr.length%2 == 0) {
      			ans.addAll(func(arr, 0));
      		}else {
      			
      			int a1 = arr[0]+arr[1];
      			int a2 = arr[1]+arr[2];
      			int a3 = arr[0]+arr[2];
      			
      			//System.out.println(a1 + " " + a2 + " " + a3);
      			
      			if(a1 != 0) {
      				if((a1 > 0 && arr[2] > 0) || (a1<0 && arr[2]<0)) {
      					ans.add(-1*arr[2]);
      					ans.add(-1*arr[2]);
      					ans.add(a1);
      				}else {
      					ans.add(Math.abs(arr[2]));
      					ans.add(Math.abs(arr[2]));
      					ans.add(Math.abs(a1));
      				}
      			}else if(a2 != 0) {
      				
      				if((a2 > 0 && arr[0] > 0) || (a2<0 && arr[0]<0)) {
      					ans.add(a2);
      					ans.add(-1*arr[0]);
      					ans.add(-1*arr[0]);
      				}else {
      					ans.add(Math.abs(a2));
      					ans.add(Math.abs(arr[0]));
      					ans.add(Math.abs(arr[0]));
      				}
      				
      			}else if(a3 != 0) {
      				
      				if((a3 > 0 && arr[1] > 0) || (a3<0 && arr[1]<0)) {
      					ans.add(-1*arr[1]);
      					ans.add(a1);
      					ans.add(-1*arr[1]);
      				}else {
      					ans.add(Math.abs(arr[1]));
      					ans.add(Math.abs(a3));
      					ans.add(Math.abs(arr[1]));
      				}
      				
      			}
      			
      			ans.addAll(func(arr, 3));
      			
      		}
      		
      		for(int num: ans) {
      			out.append(num + " ");
      		}
      		out.append("\n");
      	}
      	
      	out.flush();
  	
  	}
  	
  	public static List<Integer> func(Integer[] arr, int index) {
  		
  		List<Integer> list = new ArrayList<>();
  		for(int i=index;i<arr.length;i+=2) {
  			
  			if((arr[i] > 0 && arr[i+1] > 0) || (arr[i] < 0 && arr[i+1] < 0)) {
  				list.add(-1*arr[i+1]);
  				list.add(arr[i]);
  			}else {
  				list.add(Math.abs(arr[i+1]));
  				list.add(Math.abs(arr[i]));
  			}
  			
  		}
  		return list;
  		
  	}
  	
  
  	public static Integer[] convertToIntArray(String[] str) {
  		Integer[] arr = new Integer[str.length];
  	    for(int i=0;i<str.length;i++) {
  	    	arr[i] = Integer.parseInt(str[i]);
  	    }
  	    return arr;
  	}
  	
  	public static Long[] convertToLongArray(String[] str) {
  		Long[] arr = new Long[str.length];
  	    for(int i=0;i<str.length;i++) {
  	    	arr[i] = Long.parseLong(str[i]);
  	    }
  	    return arr;
  	}
  	
  	public static void printYes() throws IOException {
  		out.append("YES" + "\n");
  	}
  	
  	public static void printNo() throws IOException {
  		out.append("NO" + "\n");
  	}
  	
  	public static void printNumber(long num) throws IOException {
  		out.append(num + "\n");
  	}
  	
  	public static long hcf(long a, long b) {
  		if(b==0) return a;
  		return hcf(b, a%b);
  	}
  	
  	public static int findSet(int[] parent, int[] rank, int v) {
          if(v==parent[v]) {
              return v;
          }
          parent[v] = findSet(parent, rank, parent[v]);
          return parent[v];
      }
      
      public static void unionSet(int[] parent, int[] rank, int a, int b) {
          
          a = findSet(parent, rank, a);
          b = findSet(parent, rank, b);
          
          if(a == b) {
              return;
          }
          
          if(rank[a] < rank[b]) {
              int temp = a;
              a = b;
              b = temp;
          }
          
          parent[b] = a;
          if(rank[a] == rank[b]) {
              rank[a]++;
          }
          
      }
      
      public static void makeSet(int[] parent, int[] rank, int v) {
          parent[v] = v;
          rank[v] = 0;
      }
  
  }
  