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.IOException;
  import java.io.InputStreamReader;
  import java.io.PrintWriter;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.StringTokenizer;
  
  public class _1582_D {
  
      private static final FastScanner in = new FastScanner();
      private static final PrintWriter out = new PrintWriter(System.out);
      private static final PrintWriter err = new PrintWriter(System.err);
  
      public static void solve() {
          int n = in.nextInt();
          int[] a = in.nextIntArray(n);
  
          int[] b = new int[n];
  
          // a[i] * (-a[i-1]) + a[i] * a[i-1] = 0
          for (int i = 0; i < n; i++) {
              if (i % 2 == 1) {
                  b[i] = -a[i - 1];
                  b[i - 1] = a[i];
              }
          }
  
          if (n % 2 == 1) {
              // a[i] * (-a[i+2]) + a[i+1] * (-a[i+2)) + a[i+2] * (a[i] + a[i+1]) == 0
              if (a[n-3] + a[n-2] != 0) {
                  b[n-3] = b[n-2] = -a[n-1];
                  b[n-1] = a[n-3] + a[n-2];
              } else if (a[n-2] + a[n-1] != 0) {
                  b[n-2] = b[n-1] = -a[n-3];
                  b[n-3] = a[n-2] + a[n-1];
              } else if (a[n-1] + a[n-3] != 0){
                  b[n-1] = b[n-3] = -a[n-2];
                  b[n-2] = a[n-1] + a[n-3];
              }
          }
  
          validate(a, b);
  
          for (int e : b) {
              out.print(e + " ");
          }
          out.println();
      }
  
      private static void validate(int[] a, int[] b) {
          long sum = 0;
          for (int i = 0; i < a.length; i++) {
              sum += (long)a[i] * b[i];
          }
          assert sum == 0;
      }
  
      // Boilerplate
      public static void main(String[] args) {
          int t = in.nextInt();
          while (t-- > 0) {
              solve();
          }
  
          err.close();
          out.close();
      }
  
      @SuppressWarnings("unused")
      static class FastScanner {
  
          StringTokenizer tok = new StringTokenizer("");
          BufferedReader in;
  
          FastScanner() {
              in = new BufferedReader(new InputStreamReader(System.in));
          }
  
          String next() {
              while (!tok.hasMoreElements()) {
                  try {
                      tok = new StringTokenizer(in.readLine());
                  } catch (IOException e) {
                      throw new RuntimeException(e);
                  }
              }
  
              return tok.nextToken();
          }
  
          String nextLine() {
              String line;
              try {
                  line = in.readLine();
              } catch (IOException e) {
                  throw new RuntimeException(e);
              }
              return line;
          }
  
          int nextInt() {
              return Integer.parseInt(next());
          }
  
          int[] nextIntArray(int n) {
              int[] arr = new int[n];
              for (int i = 0; i < n; i++) {
                  arr[i] = nextInt();
              }
              return arr;
          }
  
          List<Integer> nextIntegerList(int n) {
              ArrayList<Integer> list = new ArrayList<>(n);
              for (int i = 0; i < n; i++) {
                  list.add(nextInt());
              }
              return list;
          }
  
          long nextLong() {
              return Long.parseLong(next());
          }
  
          long[] nextLongArray(int n) {
              long[] arr = new long[n];
              for (int i = 0; i < n; i++) {
                  arr[i] = nextLong();
              }
              return arr;
          }
  
          List<Long> nextLongList(int n) {
              ArrayList<Long> list = new ArrayList<>(n);
              for (int i = 0; i < n; i++) {
                  list.add(nextLong());
              }
              return list;
          }
  
          ArrayList<Integer>[] nextGraph(int n, int m) {
              @SuppressWarnings("unchecked")
              ArrayList<Integer>[] adj = (ArrayList<Integer>[]) new ArrayList[n];
  
              for (int i = 0; i < n; i++) {
                  adj[i] = new ArrayList<>();
              }
  
              for (int i = 0; i < m; i++) {
                  int v = nextInt();
                  int t = nextInt();
                  adj[v - 1].add(t - 1);
                  adj[t - 1].add(v - 1);
              }
  
              return adj;
          }
      }
  }