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: import sys
  from math import *
  import builtins
  import string
  import bisect
  
  alphabets = list(string.ascii_lowercase)
  ALPHABETS = list(string.ascii_uppercase)
  
  # # For getting input from input.txt file
  # sys.stdin = open('input.txt', 'r')
  #
  # # Printing the Output to output.txt file
  # sys.stdout = open('output.txt', 'w')
  
  # input = sys.stdin.readline
  
  
  def print(x, end='\n'):
      sys.stdout.write(str(x) + end)
  
  
  # IO helpers
  def get_int():
      return int(input())
  
  
  def get_list_ints():
      return list(map(int, input().split()))
  
  
  def get_char_list():
      s = input()
      return list(s[:len(s)])
  
  
  def get_tuple_ints():
      return tuple(map(int, input().split()))
  
  
  def print_iterable(p):
      print(" ".join(map(str, p)))
  
  
  def floorSearch(arr, low, high, x):
      if low > high:
          return -1
      if x >= arr[high]:
          return high
      mid = int((low + high) / 2)
      if arr[mid] == x:
          return mid
      if mid > 0 and arr[mid - 1] <= x < arr[mid]:
          return mid - 1
      if x < arr[mid]:
          return floorSearch(arr, low, mid - 1, x)
      return floorSearch(arr, mid + 1, high, x)
  
  
  def binary_search(arr, x):
      low = 0
      high = len(arr) - 1
      mid = 0
      while low <= high:
          mid = (high + low) // 2
          if arr[mid] < x:
              low = mid + 1
          elif arr[mid] > x:
              high = mid - 1
          else:
              return mid
      return high
  
  
  def main():
      p = get_int()
      for q in range(p):
          n, k = get_list_ints()
          ls = get_list_ints()
          ans = -1e12
          for i in range(max(0, n-2*k-1), n-1):
              for j in range(i+1, n):
                  ans = max(ans, (i+1)*(j+1) - k*(ls[i] | ls[j]))
          print(ans)
      pass
  
  
  if __name__ == '__main__':
      main()
  