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.*;
  
  public class D {
      static FastReader reader = new FastReader();
      static OutputWriter out = new OutputWriter(System.out);
  
      static long gcd(long a, long b) {
          if(b == 0) return a;
          return gcd(b, a % b);
      }
  
      static long lcm(long a, long b) {
          return a*b/gcd(a, b);
      }
  
      static void sort(int[] arr) {
          ArrayList<Integer> list = new ArrayList<>(arr.length);
          for (int i = 0; i < arr.length; i++) {
              list.add(arr[i]);
          }
          Collections.sort(list, Comparator.comparingInt(Math::abs));
          for(int i = 0; i < arr.length; i++) arr[i] = list.get(i);
      }
  
      public static void main(String[] args) {
          int tests = reader.nextInt();
          for (int test = 1; test <= tests; test++) {
              final int n = reader.nextInt();
              int[] arr = new int[n];
              for (int i = 0; i < n; i++) arr[i] = reader.nextInt();
              int[] ans = new int[n];
              if (n % 2 == 0) {
                  for (int i = 0; i < n; i+= 2) {
                      ans[i] = arr[i + 1];
                      ans[i + 1] = -arr[i];
                  }
              } else {
                  for (int i = 3; i < n; i+= 2) {
                      ans[i] = arr[i + 1];
                      ans[i + 1] = -arr[i];
                  }
                  if (arr[0] + arr[1] != 0) {
                      long s = arr[0] + arr[1];
                      long lcm = lcm(s, arr[2]);
                      ans[0] = (int) (lcm/s);
                      ans[1] = (int) (lcm/s);
                      ans[2] = (int) (-lcm/arr[2]);
                  } else if (arr[1] + arr[2] != 0) {
                      long s = arr[1] + arr[2];
                      long lcm = lcm(s, arr[0]);
                      ans[2] = (int) (lcm/s);
                      ans[1] = (int) (lcm/s);
                      ans[0] = (int) (-lcm/arr[0]);
                  } else if (arr[0] + arr[2] != 0) {
                      long s = arr[0] + arr[2];
                      long lcm = lcm(s, arr[1]);
                      ans[0] = (int) (lcm/s);
                      ans[2] = (int) (lcm/s);
                      ans[1] = (int) (-lcm/arr[1]);
                  }
              }
              out.println(ans);
          }
          out.flush();
      }
  
  
      static class FastReader {
          BufferedReader br;
          StringTokenizer st;
  
          public FastReader() {
              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 static class OutputWriter {
          private final PrintWriter writer;
  
          public OutputWriter(OutputStream outputStream) {
              writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(outputStream)));
          }
  
          public OutputWriter(Writer writer) {
              this.writer = new PrintWriter(writer);
          }
  
          public void print(char[] array) {
              writer.print(array);
          }
  
          public void print(Object... objects) {
              for (int i = 0; i < objects.length; i++) {
                  if (i != 0) {
                      writer.print(' ');
                  }
                  writer.print(objects[i]);
              }
          }
  
          public void print(int[] array) {
              for (int i = 0; i < array.length; i++) {
                  if (i != 0) {
                      writer.print(' ');
                  }
                  writer.print(array[i]);
              }
          }
  
          public void print(double[] array) {
              for (int i = 0; i < array.length; i++) {
                  if (i != 0) {
                      writer.print(' ');
                  }
                  writer.print(array[i]);
              }
          }
  
          public void print(long[] array) {
              for (int i = 0; i < array.length; i++) {
                  if (i != 0) {
                      writer.print(' ');
                  }
                  writer.print(array[i]);
              }
          }
  
          public void println(int[] array) {
              print(array);
              writer.println();
          }
  
          public void println(double[] array) {
              print(array);
              writer.println();
          }
  
          public void println(long[] array) {
              print(array);
              writer.println();
          }
  
          public void println() {
              writer.println();
          }
  
          public void println(Object... objects) {
              print(objects);
              writer.println();
          }
  
          public void print(char i) {
              writer.print(i);
          }
  
          public void println(char i) {
              writer.println(i);
          }
  
          public void println(char[] array) {
              writer.println(array);
          }
  
          public void printf(String format, Object... objects) {
              writer.printf(format, objects);
          }
  
          public void close() {
              writer.close();
          }
  
          public void flush() {
              writer.flush();
          }
  
          public void print(long i) {
              writer.print(i);
          }
  
          public void println(long i) {
              writer.println(i);
          }
  
          public void print(int i) {
              writer.print(i);
          }
  
          public void println(int i) {
              writer.println(i);
          }
  
          public void separateLines(int[] array) {
              for (int i : array) {
                  println(i);
              }
          }
      }
  }