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.StringTokenizer;
  
  public class VupsenPupsenAnd0 {
  
      static FastScanner fs;
      static FastWriter fw;
      static boolean checkOnlineJudge = System.getProperty("ONLINE_JUDGE") == null;
  
      private static final int mod = (int) (1e9 + 7);
  
      public static void main(String[] args) throws IOException {
  
          fs = new FastScanner();
          fw = new FastWriter();
  
          int t = 1;
          t = fs.nextInt();
          while (t-- > 0) {
              solve();
          }
  
          fw.out.close();
      }
  
      static void solve() {
  
          int n = fs.nextInt();
          int[] a = new int[n];
          for (int i = 0; i < n; i++)
              a[i] = fs.nextInt();
          int[] b = new int[n];
  
          if ((n & 1) == 1) {
              for (int i = 0; i < 2; i++) {
                  for (int j = i + 1; j < 3; j++) {
                      if (a[i] + a[j] == 0)
                          continue;
  
                      int k = 0;
                      while (i == k || j == k) {
                          k++;
                      }
  
                      b[i] = a[k];
                      b[j] = a[k];
                      b[k] = -(a[i] + a[j]);
                      util(a, n, 3, b);
                      printArr(b, n);
                      return;
                  }
              }
          }
  
  
          util(a, n, 0, b);
          printArr(b, n);
      }
  
      private static void util(int[] a, int n, int st, int[] b) {
  
          for (int i = st; i < n; i += 2) {
              b[i] = -a[i + 1];
              b[i + 1] = a[i];
          }
      }
  
      private static void printArr(int[] b, int n) {
          for (int i = 0; i < n; i++)
              fw.out.print(b[i] + " ");
          fw.out.println();
      }
  
      private static class FastScanner {
          BufferedReader br;
          StringTokenizer st;
  
          FastScanner() throws IOException {
              if (checkOnlineJudge)
                  this.br = new BufferedReader(new FileReader("src/input.txt"));
              else
                  this.br = new BufferedReader(new InputStreamReader(System.in));
  
              this.st = new StringTokenizer("");
          }
  
          public String next() {
              while (!st.hasMoreTokens()) {
                  try {
                      st = new StringTokenizer(br.readLine());
                  } catch (IOException err) {
                      err.printStackTrace();
                  }
              }
              return st.nextToken();
          }
  
          public String nextLine() {
              if (st.hasMoreTokens()) {
                  return st.nextToken("").trim();
              }
              try {
                  return br.readLine().trim();
              } catch (IOException err) {
                  err.printStackTrace();
              }
              return "";
          }
  
          public int nextInt() {
              return Integer.parseInt(next());
          }
  
          public long nextLong() {
              return Long.parseLong(next());
          }
  
          public double nextDouble() {
              return Double.parseDouble(next());
          }
      }
  
      private static class FastWriter {
          PrintWriter out;
  
          FastWriter() throws IOException {
              if (checkOnlineJudge)
                  out = new PrintWriter(new FileWriter("src/output.txt"));
              else
                  out = new PrintWriter(System.out);
          }
      }
  }
  