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.File;
  import java.io.FileInputStream;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.io.PrintStream;
  import java.io.PrintWriter;
  import java.time.Duration;
  import java.time.Instant;
  import java.util.ArrayList;
  import java.util.StringTokenizer;
  import static java.lang.Math.min;
  import static java.lang.Math.max;
  import static java.lang.Math.abs;
  
  @SuppressWarnings("unused")
  public class Main {
  	static boolean DEBUG = false;
  
  	public static void main(String[] args) throws IOException {
  		Instant start = Instant.now();
  		if (args.length == 2) {
  			System.setIn(new FileInputStream(new File("D://program//javaCPEclipse//MyJava//src//MyJava//input.txt")));
  			// System.setOut(new PrintStream(new File("output.txt")));
  			System.setErr(new PrintStream(new File("D://program//javaCPEclipse//MyJava//src//MyJava//error.txt")));
  			DEBUG = true;
  		}
  		Reader fs = new Reader();
  		PrintWriter pw = new PrintWriter(System.out);
  		int t = fs.nextInt();
  		while (t-- > 0) {
  			int n = fs.nextInt();
  			int a[] = fs.readArray(n);
  			if(n % 2 == 1) {
  				if(-a[1]-a[2] != 0) {
  					pw.print(-a[1]-a[2] + " " + a[0] + " " + a[0] + " ");
  				}
  				else {
  					pw.print(-a[1]+a[2] + " " + a[0] + " " + -a[0] + " ");
  				}
  				for(int i = 3 ; i < n ; i+=2	) {
  					pw.print(a[i + 1] + " " + -a[i] + " ");
  				}
  			}
  			else {
  				for(int i = 0 ; i < n ; i+=2) {
  					pw.print(a[i + 1] + " " + -a[i] + " ");
  				}
  			}
  			pw.println();
  		}
  		Instant end = Instant.now();
  		if (DEBUG) {
  			pw.println(Duration.between(start, end));
  		}
  		pw.close();
  	}
  
  	public static void print(long a, long b, long c, PrintWriter pw) {
  		pw.println(a + " " + b + " " + c);
  		return;
  	}
  
  	static class Reader {
  		BufferedReader br;
  		StringTokenizer st;
  
  		public Reader() {
  			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;
  		}
  
  		int[] readArray(int n) {
  			int a[] = new int[n];
  			for (int i = 0; i < n; i++)
  				a[i] = nextInt();
  			return a;
  		}
  
  		int[][] read2Array(int n, int m) {
  			int a[][] = new int[n][m];
  			for (int i = 0; i < n; i++) {
  				for (int j = 0; j < m; j++) {
  					a[i][j] = nextInt();
  				}
  			}
  			return a;
  		}
  	}
  }