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
  
  def gcd(a,b):
   while b: a,b=b,a%b
   return a
  
  def f(n,a):
   if len(set(map(abs,a)))==1:
    return [(n-1)*(a[0].__cmp__(0))]+[(-1)*(a[i].__cmp__(0)) for i in xrange(1,n)]
   r=sorted(zip(a,range(n)), key=lambda (x,y): abs(x), reverse=True); s=0
   for i in range(n):
    if s<=0:
     if r[i][0]>=0: s+=r[i][0]; r[i]=(1,r[i][1])
     else : s-=r[i][0]; r[i]=(-1,r[i][1])
    else:
     if r[i][0]>=0: s-=r[i][0]; r[i]=(-1,r[i][1])
     else: s+=r[i][0]; r[i]=(1,r[i][1])
   t=(s,0)
   r=[x for (x,y) in sorted(r,key=lambda (x,y): y)]
   if s==0: return r
   while abs(t[0])==abs(s): i=random.randint(0,n-1); t=(a[i],i)
   g=gcd(abs(t[0]),abs(s)); c1=t[0]/g; c2=s/g
   for i in xrange(len(r)): r[i]*=c1
   r[t[1]]-=c2
   s2=sum(a[i]*r[i] for i in xrange(n))
   return r
  
  
  
  for t in xrange(int(raw_input())):
   n=int(raw_input())
   a=map(int,raw_input().strip().split())
   print ' '.join(map(str,f(n,a)))
  