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.math.*;
  import java.util.*;
  
  public class Main {
  	static int mod=1000000007;
  	static MyScanner sc = new MyScanner();
  	static Output out = new Output();
  	public static void main(String[] args) {
  		int t=sc.nextInt();
  		for (int i=0;i<t;i++) {
  			solve();
  		}
  		out.flush();
  	}
  
  	public static void solve() {
  		int n=sc.nextInt();
  		int a[]=sc.nextIntArr(n);
  		int b[]=new int[n];
  		if(n%2==0) {
  			for(int i=0;i<n/2;i++) {
  				b[i]=a[n-i-1];
  				b[n-i-1]=-a[i];
  			}
  		}
  		else {
  			if(a[n-2]+a[n-3]!=0) {
  				b[n-1]=-1*(a[n-2]+a[n-3]);
  				b[n-2]=a[n-1];
  				b[n-3]=a[n-1];
  			}
  			else if(a[n-2]+a[n-1]!=0) {
  				b[n-3]=-1*(a[n-2]+a[n-1]);
  				b[n-2]=a[n-3];
  				b[n-1]=a[n-3];
  			}
  			else {
  				b[n-2]=-1*(a[n-1]+a[n-3]);
  				b[n-3]=a[n-2];
  				b[n-1]=a[n-2];
  			}
  			for(int i=0;i<(n-3)/2;i++) {
  				b[i]=a[n-i-4];
  				b[n-i-4]=-a[i];
  			}
  		}
  		
  		for(int i=0;i<n;i++)
  			out.print(b[i]+" ");
  		out.println();
  	}
  }
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  class Array{
  	static void sort(int[] arr){
  		mergesort(arr,0,arr.length-1);
  	}
  	static void sort(int[] arr,int startIndex,int endIndex){
  		mergesort(arr,startIndex,endIndex);
  	}
  
  	static void mergesort(int[] arr,int b,int e) {
  		if(b<e) {
  			int m=b+(e-b)/2;
  			mergesort(arr,b,m);
  			mergesort(arr,m+1,e);
  			merge(arr,b,m,e);
  		}
  		return;	
  	}
  	static void merge(int[] arr,int b,int m,int e) {
  		int len1=m-b+1,len2=e-m;
  		int[] l=new int[len1];
  		int[] r=new int[len2];
  		for(int i=0;i<len1;i++)l[i]=arr[b+i];
  		for(int i=0;i<len2;i++)r[i]=arr[m+1+i];
  		int i=0,j=0,k=b;
  		while(i<len1 && j<len2) {
  			if(l[i]<r[j])arr[k++]=l[i++];
  			else arr[k++]=r[j++];
  		}
  		while(i<len1)arr[k++]=l[i++];
  		while(j<len2)arr[k++]=r[j++];
  		return;
  	}
  	
  	//2d sort
  //	static void sort(int[][] arr){
  //		mergesort(arr,0,arr.length-1);
  //	}
  //	static void sort(int[][] arr,int startIndex,int endIndex){
  //		mergesort(arr,startIndex,endIndex);
  //	}
  //
  //	static void mergesort(int[][] arr,int b,int e) {
  //		if(b<e) {
  //			int m=b+(e-b)/2;
  //			mergesort(arr,b,m);
  //			mergesort(arr,m+1,e);
  //			merge(arr,b,m,e);
  //		}
  //		return;	
  //	}
  //	static void merge(int[][] arr,int b,int m,int e) {
  //		int len1=m-b+1,len2=e-m;
  //		int[][] l=new int[len1][2];
  //		int[][] r=new int[len2][2];
  //		for(int i=0;i<len1;i++) {
  //			l[i][0]=arr[b+i][0];
  //			l[i][1]=arr[b+i][1];
  //		}
  //		for(int i=0;i<len2;i++) {
  //			r[i][0]=arr[m+1+i][0];
  //			r[i][1]=arr[m+1+i][1];
  //		}
  //		int i=0,j=0,k=b;
  //		while(i<len1 && j<len2) {
  //			if(l[i][0]<r[j][0]) {
  //				arr[k++][0]=l[i++][0];
  //				arr[k-1][1]=l[i-1][1];
  //			}
  //			else {
  //				arr[k++][0]=r[j++][0];
  //				arr[k-1][1]=r[j-1][1];
  //			}
  //		}
  //		while(i<len1) {
  //			arr[k++][0]=l[i++][0];
  //			arr[k-1][1]=l[i-1][1];
  //		}
  //		while(j<len2) {
  //			arr[k++][0]=r[j++][0];
  //			arr[k-1][1]=r[j-1][1];
  //		}
  //		return;
  //	}
  	
  }
  class MyScanner {
  
  	BufferedReader br;
  	StringTokenizer st;
  
  	public MyScanner() {
  		br = new BufferedReader(new InputStreamReader(System.in));
  	}
  
  	String next() {
  		while (st == null || !st.hasMoreElements()) {
  			try {
  				st = new StringTokenizer(br.readLine());
  			} catch (IOException e) {
  				e.printStackTrace();
  			}
  		}
  		return st.nextToken();
  	}
  
  	int nextInt() {
  		return Integer.parseInt(next());
  	}
  
  	long nextLong() {
  		return Long.parseLong(next());
  	}
  
  	double nextDouble() {
  		return Double.parseDouble(next());
  	}
  
  	String nextLine() {
  		String str = "";
  		try {
  			str = br.readLine();
  		} catch (IOException e) {
  			e.printStackTrace();
  		}
  		return str;
  	}
  
  	public int[] nextIntArr(int n) {
  		int a[] = new int[n];
  		for (int i = 0; i < n; i++)
  			a[i] = nextInt();
  		return a;
  	}
  
  	public long[] nextLongArr(int n) {
  		long a[] = new long[n];
  		for (int i = 0; i < n; i++)
  			a[i] = nextLong();
  		return a;
  	}
  
  	public double[] nextDoubleArr(int n) {
  		double a[] = new double[n];
  		for (int i = 0; i < n; i++)
  			a[i] = nextDouble();
  		return a;
  	}
  
  	public String[] nextArr(int n) {
  		String a[] = new String[n];
  		for (int i = 0; i < n; i++)
  			a[i] = next();
  		return a;
  	}
  
  	public String[] nextLineArr(int n) {
  		String a[] = new String[n];
  		for (int i = 0; i < n; i++)
  			a[i] = nextLine();
  		return a;
  	}
  }
  
  class Output {
  	BufferedWriter out = new BufferedWriter(new OutputStreamWriter(System.out));
  	public void print() {}
  	public void println() {
  		try {
  			out.write("\n");
  		} catch (Exception e) {}
  	}
  	public void print(Object s) {
  		try {
  			out.write(s + "");
  		} catch (Exception e) {}
  	}
  	public void println(Object s) {
  		try {
  			out.write(s + "\n");
  		} catch (Exception e) {}
  	}
  	public void flush() {
  		try {
  			out.flush();
  		} catch (Exception e) {}
  	}
  }