description: You are given n integers a_1, a_2, …, a_n and an integer k. Find the maximum value of i ⋅ j - k ⋅ (a_i | a_j) over all pairs (i, j) of integers with 1 ≤ i < j ≤ n. Here, | is the [bitwise OR operator](https://en.wikipedia.org/wiki/Bitwise_operation#OR).
  
  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 two integers n (2 ≤ n ≤ 10^5) and k (1 ≤ k ≤ min(n, 100)).
  
  The second line of each test case contains n integers a_1, a_2, …, a_n (0 ≤ a_i ≤ n).
  
  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 i ⋅ j - k ⋅ (a_i | a_j).
  
  Example
  
  Input
  
  
  4
  3 3
  1 1 3
  2 2
  1 2
  4 3
  0 1 2 3
  6 6
  3 2 0 0 5 6
  
  
  Output
  
  
  -1
  -4
  3
  12
  
  Note
  
  Let f(i, j) = i ⋅ j - k ⋅ (a_i | a_j).
  
  In the first test case, 
  
    * f(1, 2) = 1 ⋅ 2 - k ⋅ (a_1 | a_2) = 2 - 3 ⋅ (1 | 1) = -1. 
    * f(1, 3) = 1 ⋅ 3 - k ⋅ (a_1 | a_3) = 3 - 3 ⋅ (1 | 3) = -6. 
    * f(2, 3) = 2 ⋅ 3 - k ⋅ (a_2 | a_3) = 6 - 3 ⋅ (1 | 3) = -3. 
  
  
  
  So the maximum is f(1, 2) = -1.
  
  In the fourth test case, the maximum is f(3, 4) = 12.
solution: from collections import deque
  import heapq
  from math import sqrt
  import operator
  from operator import itemgetter
  import sys
  
  import copy
  
   
  inf_var = 0
  if inf_var == 1:
      inf = open('input.txt', 'r')
  else:
      inf = sys.stdin
   
  input = inf.readline
  # sys.stdout = open('output.txt', 'w')
   
  def read_one_int():
      return int(input().rstrip('\n'))
  
  
  def read_one_float():
      return float(input().rstrip('\n'))
   
   
  def read_list_of_ints():
      res = [int(val) for val in (input().rstrip('\n')).split(' ')]
      return res
   
  def read_str():
      return input().rstrip()
  
  
  def to_left_diag(i, j):
      return i + j
  
  
  def to_right_diag(i, j):
      return i - j
  
  
  class Vertex:
      def __init__(self):
          self.next = {}
          self.terminal = False
          self.cnt = 1
  
  
  def add_str(trie, cur_str):
      vertices_cnt = 0
      cur_node = trie
      for ch in cur_str:
          if ch in cur_node.next:
              cur_node = cur_node.next[ch]
              cur_node.cnt += 1
          else:
              cur_node.next[ch] = Vertex()
              vertices_cnt += 1
              cur_node = cur_node.next[ch]
  
      cur_node.terminal = True
      return vertices_cnt
  
  
  def main():
      tests = read_one_int()
  
      inf = 10 ** 8
  
      for _ in range(tests):
          n, k = read_list_of_ints()
          elements = read_list_of_ints()
  
          st = 0
          if n > 1000:
              st = n - 1000
  
          cur_res = -inf
  
          for i in range(st, n - 1):
              for j in range(i + 1, n):
                  cur_res = max(cur_res, (i + 1) * (j + 1) - k * (elements[i] | elements[j]))
  
          print(cur_res)
  
  
  if __name__== '__main__':
      main()
  