for _ in range(int(input())):
  n=int(input())
  a=[*map(int,input().split())]
  minus=[i for i in a if i<0]
  plus=[i for i in a if i>0]
  ans=1<<60
  minus.sort()
  plus.sort()
  if 0 in a:
    ans=0
  if minus and plus:
    ans=min(ans,minus[-1]*plus[0])
  if len(minus)>1:
    ans=min(ans,minus[-2]*minus[-1])
  if len(plus)>1:
    ans=min(ans,plus[0]*plus[1])
  print(ans)