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.lang.reflect.Array;
  import java.math.BigInteger;
  import java.util.*;
  import java.util.BitSet;
  import java.util.function.BinaryOperator;
  
  public class D {
      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;
          }
      }
  
      static FastReader s = new FastReader();
      static PrintWriter out = new PrintWriter(System.out);
  
      private static int[] rai(int n) {
          int[] arr = new int[n];
          for (int i = 0; i < n; i++) {
              arr[i] = s.nextInt();
          }
          return arr;
      }
  
      private static int[][] rai(int n, int m) {
          int[][] arr = new int[n][m];
          for (int i = 0; i < n; i++) {
              for (int j = 0; j < m; j++) {
                  arr[i][j] = s.nextInt();
              }
          }
          return arr;
      }
  
      private static long[] ral(int n) {
          long[] arr = new long[n];
          for (int i = 0; i < n; i++) {
              arr[i] = s.nextLong();
          }
          return arr;
      }
  
      private static long[][] ral(int n, int m) {
          long[][] arr = new long[n][m];
          for (int i = 0; i < n; i++) {
              for (int j = 0; j < m; j++) {
                  arr[i][j] = s.nextLong();
              }
          }
          return arr;
      }
  
      private static int ri() {
          return s.nextInt();
      }
  
      private static long rl() {
          return s.nextLong();
      }
  
      private static String rs() {
          return s.next();
      }
  
  
      static long gcd(long a,long b)
      {
          if(b==0)
          {
              return a;
          }
          return gcd(b,a%b);
      }
  
      static int MOD=(int)1e9+7;
  
      public static int primeFactors(long n)
      {
          // Print the number of 2s that divide n
          int count=0;
          while (n % 2 == 0) {
              count++;
              n /= 2;
          }
  
          // n must be odd at this point.  So we can
          // skip one element (Note i = i +2)
          for (long i = 3; i * i<=n; i += 2) {
              // While i divides n, print i and divide n
              while (n % i == 0) {
                  count++;
                  n /= i;
              }
          }
  
          // This condition is to handle the case whien
          // n is a prime number greater than 2
          if (n > 2)
              count++;
  
          return count;
      }
  
      static class Node
      {
          int val, i;
  
          public Node(int val, int i) {
              this.val = val;
              this.i = i;
          }
      }
      public static void main(String[] args) {
          StringBuilder ans = new StringBuilder();
          int t = ri();
  //        int t=1;
          while(t-- >0)
          {
              int n=ri();
              int[] arr=rai(n);
              int[] res = new int[n];
              if(n%2==0)
              {
  
                  for(int i=0;i<n;i+=2)
                  {
                      res[i] = -arr[i+1];
                      res[i+1]=arr[i];
                  }
  
  
              }
              else {
                  for(int i=0;i<n-3;i+=2)
                  {
                      res[i] = -arr[i+1];
                      res[i+1]=arr[i];
                  }
  
                  int val = arr[n-1]+arr[n-2];
                  if(val!=0) {
                      res[n - 3] = -val;
                      res[n - 2] = arr[n - 3];
                      res[n - 1] = arr[n - 3];
                  }
                  else
                  {
                      val = arr[n-1]+arr[n-3];
                      if(val!=0) {
                          res[n - 2] = -val;
                          res[n - 1] = arr[n - 2];
                          res[n - 3] = arr[n - 2];
                      }
                      else
                      {
                          val = arr[n-2]+arr[n-3];
                          res[n-1] = -val;
                          res[n-2]=arr[n-1];
                          res[n-3]=arr[n-1];
                      }
                  }
  
              }
  
              for(int i:res)
              {
                  ans.append(i).append(" ");
              }
              ans.append("\n");
  
  //            int sum=0;
  //            for(int i=0;i<n;i++)
  //            {
  //                sum+=arr[i]*res[i];
  //            }
  //            System.out.println(sum);
  
          }
          out.print(ans.toString());
          out.flush();
      }
  }