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 io, os
  import sys 
  from sys import stdin
  
  from bisect import bisect_left, bisect_right
  from collections import defaultdict, deque, namedtuple
  from math import gcd, ceil, floor, factorial
  from itertools import combinations, permutations
  
  input = sys.stdin.buffer.readline
  # input = io.BytesIO(os.read(0,os.fstat(0).st_size)).readline
  # input = sys.stdin.readline
  
  def work(n, a):
      ans = [0] * n 
      if n % 2 == 0:
          for i in range(0, n, 2):
              ans[i] = a[i + 1] * (-1)
              ans[i + 1] = a[i]
          return ans 
      
      if a[0] + a[1] == 0:
          if a[0] + a[2] == 0:
              ans[0] = (a[1] + a[2]) * (-1)
              ans[1] = ans[2] = a[0]
          else:
              ans[1] = (a[0] + a[2]) * (-1)
              ans [0] = ans[2] = a[1]
      else:
          ans[2] = (a[0] + a[1]) * (-1)
          ans[0] = ans[1] = a[2] 
   
      for i in range(3, n, 2):
          ans[i] = a[i + 1] * (-1)
          ans[i + 1] = a[i]
      return ans 
  
  
  def main():
      test = int(input())
  
      for idt in range(test):
          n = int(input())
          # n, m = map(int, input().split())
          a = list(map(int, input().split()))
          ans = work(n, a)
          t = 0 
          for i in range(n):
              t += ans[i] * a[i]
              print(ans[i], end=" ")
          print()
          
      return 
  
  
  if __name__ == '__main__':
      main()