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 random
  import sys
  
  
  def input():
      return sys.stdin.readline().strip('\n')
  
  
  def cin_int_ls():
      return list(map(int, input().split()))
  
  
  def cin_int():
      return int(input())
  
  
  import math
  
  
  def check(s, ans):
      cc = 0
      for i in range(len(s)):
          cc += s[i] * ans[i]
  
      print(cc == 0 and 0 not in ans, cc)
  
  
  def sv(s):
      ans = [0 for _ in s]
      if len(s) % 2 == 0:
          for i in range(len(s) // 2):
              a, b = s[i], s[-i - 1]
              gcd = math.gcd(a, b)
              aa, bb = b // gcd, a // gcd
              ans[i] = aa
              ans[-i - 1] = -bb
          return ans
      else:
          for i in range(len(s) // 2 - 1):
              a, b = s[i], s[-i - 1]
              gcd = math.gcd(a, b)
              aa, bb = b // gcd, a // gcd
              ans[i] = aa
              ans[-i - 1] = -bb
          mid1, mid2, mid3 = len(s) // 2 - 1, len(s) // 2, len(s) // 2 + 1
          a, b, c = s[mid1], s[mid2], s[mid3]
          if a + b != 0:
              a, b = a + b, c
              mid1, mid2, mid3 = mid1, mid2, mid3
          elif a + c != 0:
              a, b = a + c, b
              mid1, mid2, mid3 = mid1, mid3, mid2
          elif c + b != 0:
              a, b = b + c, a
              mid1, mid2, mid3 = mid2, mid3, mid1
          gcd = math.gcd(a, b)
          aa, bb = b // gcd, a // gcd
          ans[mid1] = aa
          ans[mid2] = aa
          ans[mid3] = -bb
  
          return ans
  
  
  def main():
      for _ in range(cin_int()):
          cin_int()
          s = cin_int_ls()
          ans = sv(s)
          # check(s, ans)
          print(*ans)
  
  
  if __name__ == '__main__':
      # a = sv([1, 2, 3])
      # check(a, [1, 2, 3])
      # print(a)
      main()
  