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.BufferedWriter;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.io.OutputStreamWriter;
  import java.util.ArrayList;
  import java.util.StringTokenizer;
  
  public class JavaApplication1 {
  
      static int num = 0;
      static long mod = (long) 1e9 + 7;
  
      public static void main(String[] args) throws IOException {
          BufferedWriter print = new BufferedWriter(new OutputStreamWriter(System.out));
          fast in = new fast();
          int t = in.nextInt();
          while(t--!=0){
              int n=in.nextInt();
              int[]arrA=new int[n];
              for (int i = 0; i < n; i++) {
                  arrA[i]=in.nextInt();
              }
              int[]arrB=new int[n];
              if(n%2==0){
                  for (int i = 0; i < n; i+=2) {
                      arrB[i]=arrA[i+1];
                      arrB[i+1]=-arrA[i];
                  }
              }else{
                  if(arrA[0]!=arrA[2]){
                      arrB[0]=-arrA[1];
                      arrB[1]=arrA[0]-arrA[2];
                      arrB[2]=arrA[1];
                  }else{
                      arrB[0]=-arrA[1];
                      arrB[1]=arrA[0]+arrA[2];
                      arrB[2]=-arrA[1];
                  }
                  for (int i = 3; i < n; i+=2) {
                      arrB[i]=arrA[i+1];
                      arrB[i+1]=-arrA[i];
                  }
              }
              for (int i = 0; i < n; i++) {
                  System.out.print(arrB[i]+" ");
              }
              System.out.println("");
          }
      }
  
      public static long binpow(long a, long b) {
          a %= mod;
          long out = 1;
          while (b > 0) {
              if ((b & 1) != 1) {
              } else {
                  out = (out * a % mod);
              }
              a = (a * a % mod);
              b >>= 1;
          }
          return out;
      }
  
      static long LowerBound(long a[], long x) {
          long l = -1, r = a.length;
          while (l + 1 < r) {
              long m = (l + r) >>> 1;
              if (a[(int) m] >= x) {
                  r = m;
              } else {
                  l = m;
              }
          }
          return r;
      }
  
      public static boolean isPrime(long num) {
          if (num <= 1) {
              return false;
          } else {
              long sq = (long) Math.sqrt(num) + 1;
              for (long i = 2; i < sq; i++) {
                  if (num % i == 0) {
                      return false;
                  }
              }
              return true;
          }
      }
  
      public static boolean checkPalindrome(String x) {
          String temp = "";
          if (x.length() % 2 == 0) {
              for (int i = x.subSequence(x.length() / 2, x.length()).length() - 1; i >= 0; i--) {
                  temp += x.subSequence(x.length() / 2, x.length()).charAt(i);
              }
              return x.substring(0, x.length() / 2).equals(temp);
          } else {
              for (int i = x.subSequence(x.length() / 2, x.length()).length() - 1; i > 0; i--) {
                  temp += x.subSequence(x.length() / 2, x.length()).charAt(i);
              }
              return x.substring(0, x.length() / 2).equals(temp);
          }
      }
  
      public static boolean isVowel(char c) {
          if (c == 'a' || c == 'e' || c == 'i' || c == 'o' || c == 'u') {
              return true;
          } else {
              return false;
          }
      }
  
  //    public static void sub(String s, String ans) {
  //        if (s.length() == 0) {
  //            arr.add(ans);
  //            return;
  //        }
  //        sub(s.substring(1), ans + s.charAt(0));
  //        sub(s.substring(1), ans);
  //    }
      public static long gcd(long a, long b) {
          if (a == 0) {
              return b;
          }
          return gcd(b % a, a);
      }
  
      public static long lcm(long a, long b) {
          return (a / gcd(a, b)) * b;
      }
  
      static class fast {
  
          BufferedReader br;
          StringTokenizer st;
  
          public fast() {
              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());
          }
  
          double nextFloat() {
              return Float.parseFloat(next());
          }
  
          String nextLine() {
              String str = "";
              try {
                  str = br.readLine();
              } catch (IOException e) {
                  e.printStackTrace();
              }
              return str;
          }
      }
  }