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 D {
  
  	//	1
  	//	10
  	//	2 5 -1 -7 1 9 -10 18 3 26
  
  	public static void main(String[] args)throws IOException {
  
  		FastScanner scan = new FastScanner();
  		PrintWriter output = new PrintWriter(System.out);
  		int t = scan.nextInt();
  		for(int tt = 0;tt<t;tt++) {
  			int n = scan.nextInt();
  			int arr[] = scan.readArray(n);
  			int ans[] = new int[n];
  			for(int i = 0;i<n-1;i+=2) {
  				ans[i] = arr[i+1];
  				ans[i+1] = -arr[i];
  			}
  			if(n%2==1) {
  				int a = arr[n-3], b = arr[n-2], c = arr[n-1];
  				if(a+b!=0) {
  					ans[n-3] = c;
  					ans[n-2] = c;
  					ans[n-1] = -(a+b);
  				}
  				else if(b+c!=0) {
  					ans[n-3] = -(b+c);
  					ans[n-2] = a;
  					ans[n-1] = a;
  				}
  				else if(a+c!=0) {
  					ans[n-3] = b;
  					ans[n-2] = -(a+c);
  					ans[n-1] = b;
  				}
  			}
  		for(int j : ans) output.print(j+" ");
  		//			int sum = 0;
  		//			for(int i = 0;i<n;i++) {
  		//				sum+= arr[i]*ans[i];
  		//			}
  		output.println();
  		//			output.println(sum);
  	}
  	output.flush();
  
  }
  
  public static int[] sort(int arr[]) {
  
  	List<Integer> list = new ArrayList<>();
  	for(int i:arr)
  		list.add(i);
  	Collections.sort(list);
  	for(int i = 0;i<list.size();i++) {
  		arr[i] = list.get(i);
  	}
  	return arr;
  
  }
  
  public static int gcd(int a, int b) {
  	if(a == 0) return b;
  	return gcd(b%a, a);
  }
  
  static boolean isPrime(int n) {
  	if (n <= 1) return false;
  	else if (n == 2) return true;
  	else if (n % 2 == 0) return false;
  	for (int i = 3; i <= Math.sqrt(n); i += 2) if (n % i == 0) return false;
  	return true;
  }
  
  public static void printArray(int arr[]) {
  	for(int i:arr) System.out.print(i+" ");
  	System.out.println();
  }
  
  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) {
  				e.printStackTrace();
  			}
  		return st.nextToken();
  	}
  
  	int nextInt() {
  		return Integer.parseInt(next());
  	}
  	int[] readArray(int n) {
  		int[] a=new int[n];
  		for (int i=0; i<n; i++) a[i]=nextInt();
  		return a;
  	}
  	long nextLong() {
  		return Long.parseLong(next());
  	}
  
  	double nextDouble() {
  		return Double.parseDouble(next());
  	}
  }
  
  }
  