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.DataInputStream;
  import java.io.FileInputStream;
  import java.io.IOException;
  
  public class O4 {
      private static String solve(int n, int[] a) {
  
          if (n == 2) {
              return a[1] + " " + (-a[0]);
          }
          int res[] = new int[n];
          if (n % 2 == 0) {
              diagonalAlignment(a, res, n);
          } else {
  
              diagonalAlignment(a, res, n - 3);
              if ( a[n - 3] + a[n - 2] != 0)
              {
                  res[n - 1] = a[n - 3] + a[n - 2];
                  res[n - 2] = -a[n - 1];
                  res[n - 3] = -a[n - 1];
              }
  
              else if (a[n - 1] + a[n - 2] != 0){
                  res[n - 3] = a[n - 1] + a[n - 2];
                  res[n - 2] = -a[n - 3];
                  res[n - 1] = -a[n - 3];
              }
              else {
                  res[n - 2] = a[n - 1] + a[n - 3];
                  res[n - 1] = -a[n - 2];
                  res[n - 3] = -a[n - 2];
  
              }
          }
  
  
          return formattedArray(res);
  
      }
  
      private static void diagonalAlignment(int[] a, int[] res, int n) {
  
  
          for (int i = 0; i < n; i += 2) {
              res[i + 1] = -a[i];
              res[i] = a[i + 1];
          }
  
  
      }
  
  
      public static void main(String[] args)
              throws IOException {
          Scanner s = new Scanner();
          int t = 1;
          t = s.nextInt();
          StringBuilder ans = new StringBuilder();
          int count = 0;
          while (t-- > 0) {
              int n = s.nextInt();
  
              int a[] = new int[n];
              getInputs(s, a, n);
  
  
              ans.append(solve(n, a)).append("\n");
          }
          System.out.println(ans.toString());
      }
  
      static class Scanner {
          final private int BUFFER_SIZE = 1 << 16;
          private DataInputStream din;
          private byte[] buffer;
          private int bufferPointer, bytesRead;
  
          public Scanner() {
              din = new DataInputStream(System.in);
              buffer = new byte[BUFFER_SIZE];
              bufferPointer = bytesRead = 0;
          }
  
          public Scanner(String file_name) throws IOException {
              din = new DataInputStream(
                      new FileInputStream(file_name));
              buffer = new byte[BUFFER_SIZE];
              bufferPointer = bytesRead = 0;
          }
  
          public String readLine() throws IOException {
              byte[] buf = new byte[64]; // line length
              int cnt = 0, c;
              while ((c = read()) != -1) {
                  if (c == '\n') {
                      if (cnt != 0) {
                          break;
                      } else {
                          continue;
                      }
                  }
                  buf[cnt++] = (byte) c;
              }
              return new String(buf, 0, cnt);
          }
  
          public int nextInt() throws IOException {
              int ret = 0;
              byte c = read();
              while (c <= ' ') {
                  c = read();
              }
              boolean neg = (c == '-');
              if (neg)
                  c = read();
              do {
                  ret = ret * 10 + c - '0';
              } while ((c = read()) >= '0' && c <= '9');
  
              if (neg)
                  return -ret;
              return ret;
          }
  
          public long nextLong() throws IOException {
              long ret = 0;
              byte c = read();
              while (c <= ' ')
                  c = read();
              boolean neg = (c == '-');
              if (neg)
                  c = read();
              do {
                  ret = ret * 10 + c - '0';
              } while ((c = read()) >= '0' && c <= '9');
              if (neg)
                  return -ret;
              return ret;
          }
  
          public double nextDouble() throws IOException {
              double ret = 0, div = 1;
              byte c = read();
              while (c <= ' ')
                  c = read();
              boolean neg = (c == '-');
              if (neg)
                  c = read();
  
              do {
                  ret = ret * 10 + c - '0';
              } while ((c = read()) >= '0' && c <= '9');
  
              if (c == '.') {
                  while ((c = read()) >= '0' && c <= '9') {
                      ret += (c - '0') / (div *= 10);
                  }
              }
  
              if (neg)
                  return -ret;
              return ret;
          }
  
          private void fillBuffer() throws IOException {
              bytesRead = din.read(buffer, bufferPointer = 0,
                      BUFFER_SIZE);
              if (bytesRead == -1)
                  buffer[0] = -1;
          }
  
          private byte read() throws IOException {
              if (bufferPointer == bytesRead)
                  fillBuffer();
              return buffer[bufferPointer++];
          }
  
          public void close() throws IOException {
              if (din == null)
                  return;
              din.close();
          }
      }
  
      public static long norm(long a, long MOD) {
          return ((a % MOD) + MOD) % MOD;
      }
  
      public static long msub(long a, long b, long MOD) {
          return norm(norm(a, MOD) - norm(b, MOD), MOD);
  
      }
  
      public static long madd(long a, long b, long MOD) {
          return norm(norm(a, MOD) + norm(b, MOD), MOD);
  
      }
  
      public static long mMul(long a, long b, long MOD) {
          return norm(norm(a, MOD) * norm(b, MOD), MOD);
  
  
      }
  
      public static long mDiv(long a, long b, long MOD) {
          return norm(norm(a, MOD) / norm(b, MOD), MOD);
      }
  
      public static String formattedArray(int a[]) {
          StringBuilder res = new StringBuilder("");
          for (int e : a)
              res.append(e).append(" ");
          return res.toString().trim();
  
      }
  
      private static void getInputs(Scanner s, int[] a, int n) throws IOException {
          for (int i = 0; i < n; i++) {
              a[i] = s.nextInt();
          }
      }
  }
  