description: You are given n integers a_1, a_2, …, a_n. Find the maximum value of max(a_l, a_{l + 1}, …, a_r) ⋅ min(a_l, a_{l + 1}, …, a_r) over all pairs (l, r) of integers for which 1 ≤ l < r ≤ n.
  
  Input
  
  The first line contains a single integer t (1 ≤ t ≤ 10 000) — the number of test cases.
  
  The first line of each test case contains a single integer n (2 ≤ n ≤ 10^5).
  
  The second line of each test case contains n integers a_1, a_2, …, a_n (1 ≤ a_i ≤ 10^6).
  
  It is guaranteed that the sum of n over all test cases doesn't exceed 3 ⋅ 10^5.
  
  Output
  
  For each test case, print a single integer — the maximum possible value of the product from the statement.
  
  Example
  
  Input
  
  
  4
  3
  2 4 3
  4
  3 2 3 1
  2
  69 69
  6
  719313 273225 402638 473783 804745 323328
  
  
  Output
  
  
  12
  6
  4761
  381274500335
  
  Note
  
  Let f(l, r) = max(a_l, a_{l + 1}, …, a_r) ⋅ min(a_l, a_{l + 1}, …, a_r).
  
  In the first test case, 
  
    * f(1, 2) = max(a_1, a_2) ⋅ min(a_1, a_2) = max(2, 4) ⋅ min(2, 4) = 4 ⋅ 2 = 8. 
    * f(1, 3) = max(a_1, a_2, a_3) ⋅ min(a_1, a_2, a_3) = max(2, 4, 3) ⋅ min(2, 4, 3) = 4 ⋅ 2 = 8. 
    * f(2, 3) = max(a_2, a_3) ⋅ min(a_2, a_3) = max(4, 3) ⋅ min(4, 3) = 4 ⋅ 3 = 12. 
  
  
  
  So the maximum is f(2, 3) = 12.
  
  In the second test case, the maximum is f(1, 2) = f(1, 3) = f(2, 3) = 6.
solution: from sys import stdin, stdout
  print = stdout.write
  input = stdin.readline
  
  
  class Node:
      def __init__(self, start, end, min, max):
          self.start, self.end = start, end
          self.min, self.max = min, max
  
      def __repr__(self):
          return f"{self.start}-{self.end} (min:{self.min}, max: {self.max})\n"
  
  class BinaryTree:
      def __init__(self, array, length):
          self.array = [None for _ in range(self.get_msb(length)-1)] + \
                       [Node(i, i, array[i], array[i]) for i in range(length)] + \
                       [None for _ in range(self.get_msb(length)-length)]
          for i in range(len(self.array)//2-1, -1, -1):
              left = (i<<1) + 1
              right = left+1
              left, right = self.array[left], self.array[right]
              if left is None:
                  continue
              else:
  
                  start, end = left.start, left.end
                  _min, _max = left.min, left.max
                  if right is not None:
                      end = right.end
                      _min, _max = min(_min, right.min), max(_max, right.max)
  
                  node = Node(start, end, _min, _max)
                  self.array[i] = node
          print(str(self.array))
  
      def get_msb(self, n):
          if not n:
              return 0
  
          msb = 1
  
          while (n > 1):
              n = n>>1
              msb += 1
  
          return (1 << msb)
  
  def solve_test():
      n = int(input())
      a = [int(x) for x in input().split()]
      _max = 0
      for i in range(n-1):
          _max = max(_max, a[i]*a[i+1])
      return _max
  
  def main(args=None):
      tests = int(input())
      for _ in range(tests):
          print(f"{solve_test()}\n")
  
  if __name__ == '__main__':
      main()