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: // Author : RegalBeast
  
  import java.io.*;
  import java.util.*;
  import java.util.concurrent.*;
  
  public class Main implements Runnable {
    static Input in = new Input();
    static PrintWriter out = Output();
    
    public static void main(String[] args) {
      new Thread(null, new Main(), String.join(
                                    "All that is gold does not glitter,",
                                    "Not all those who wander are lost;",
                                    "The old that is strong does not wither,",
                                    "Deep roots are not reached by the frost.",
                                    
                                    "From the ashes a fire shall be woken,",
                                    "A light from the shadows shall spring;",
                                    "Renewed shall be blade that was broken,",
                                    "The crownless again shall be king."
                                  ), 1<<25).start();
    }
  
    public void run() {
      int tests = in.nextInt();
  
      for (int t = 0; t < tests; t++) {
        int n = in.nextInt();
  
        int[] a = new int[n];
        for (int i = 0; i < n; i++) {
          a[i] = in.nextInt();
        }
  
        int[] b = new int[n];
        setB(a, b, 0);
  
        for (var num : b) {
          out.print(num + " ");
        }
        out.println();
      }
      
      in.close();
      out.close();
    }
  
    private static void setB(int[] a, int[] b, int idx) {
      int remaining = a.length-idx;
      if (remaining == 0) {
        return;
      }
      int toSettle = 2 + (remaining & 1);
      if (toSettle == 2) {
        b[idx] = -a[idx+1];
        b[idx+1] = a[idx];
        setB(a, b, idx+2);
      } else {
        if (a[idx] + a[idx+1] != 0) {
          b[idx] = b[idx+1] = -a[idx+2];
          b[idx+2] = a[idx] + a[idx+1];
        } else if (a[idx+1] + a[idx+2] != 0) {
          b[idx+1] = b[idx+2] = -a[idx];
          b[idx] = a[idx+1] + a[idx+2];
        } else {
          b[idx] = b[idx+2] = -a[idx+1];
          b[idx+1] = a[idx] + a[idx+2];
        }
        // int g = gcd(Math.abs(a[idx]), Math.abs(a[idx+1]));
  
        // b[idx+2] = 1;
        // if (a[idx+2] % g > 0) {
        //   a[idx+2] *= g;
        //   b[idx+2] *= g;
        // }
        // int[] xy = new int[2];
        // findSolution(a[idx], a[idx+1], a[idx+2], xy);
        // b[idx] = -xy[0];
        // b[idx+1] = -xy[1];
        // while (b[idx] == 0 || b[idx+1] == 0) {
        //   b[idx] += a[idx+1] / g;
        //   b[idx+1] -= a[idx] / g;
        // }
        setB(a, b, idx+3);
      }
    }
  
    private static int extendedGCD(int num1, int num2, int[] xy) {
      if (num2 == 0) {
        xy[0] = 1;
        xy[1] = 0;
        return num1;
      }
  
      int[] nextXY = new int[2];
      int g = extendedGCD(num2, num1 % num2, nextXY);
      xy[0] = nextXY[1];
      xy[1] = nextXY[0] - nextXY[1] * (num1 / num2);
      return g;
    }
  
    private static boolean findSolution(int a, int b, int c, int[] xy) {
      int g = extendedGCD(Math.abs(a), Math.abs(b), xy);
      if (c % g > 0) {
        return false;
      }
  
      xy[0] *= c / g;
      xy[1] *= c / g;
      if (a < 0) {
        xy[0] = -xy[0];
      }
      if (b < 0) {
        xy[1] = -xy[1];
      }
      return true;
    }
  
    private static int gcd(int num1, int num2) {
      if (num1 == 0) {
        return num2;
      }
      return gcd(num2 % num1, num1);
    }
    
    static PrintWriter Output() {
      return new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));
    }
    
    static PrintWriter Output(String fileName) {
      PrintWriter pw = null;
      try {
        pw = new PrintWriter(new BufferedWriter(new FileWriter(fileName)));
      } catch (IOException ex) {
        ex.printStackTrace();
      }
      return pw;
    }
  }
  
  class Input {
    BufferedReader br;
    StringTokenizer st;
    public Input() {
      br = new BufferedReader(new InputStreamReader(System.in));
    }
  
    public Input(String fileName) {
      try {
        br = new BufferedReader(new FileReader(fileName));
      } catch (IOException ex) {
        ex.printStackTrace();
      }
    }
  
    public String next() {
      while (st == null || !st.hasMoreElements()) {
        try {
          st = new StringTokenizer(br.readLine());
        } catch (IOException ex) {
          ex.printStackTrace();
        }
      }
      return st.nextToken();
    }
  
    public int nextInt() {
      return Integer.parseInt(next());
    }
  
    public long nextLong() {
      return Long.parseLong(next());
    }
  
    public Float nextFloat() {
      return Float.parseFloat(next());
    }
  
    public Double nextDouble() {
      return Double.parseDouble(next());
    }
  
    public String nextLine() {
      if (st != null && st.hasMoreElements()) {
        StringBuilder sb = new StringBuilder();
        while (st.hasMoreElements()) {
          sb.append(next());
        }
        return sb.toString();
      }
  
      String str = null;
      try {
        str = br.readLine();
      } catch (IOException ex) {
        ex.printStackTrace();
      }
      return str;
    }
  
    public void close() {
      try {
        br.close();
      } catch (IOException ex) {
        ex.printStackTrace();
      }
    }
  }
  