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 java.io.*;
  import java.util.*;
  
  public class MainB {
      static class InputReader {
          public BufferedReader reader;
          public StringTokenizer tokenizer;
          public InputReader(InputStream stream) {
              reader = new BufferedReader(new InputStreamReader(stream), 32768);
              tokenizer = null;
          }
          public String next() {
              while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                  try {
                      tokenizer = new StringTokenizer(reader.readLine());
                  } catch (IOException e) {
                      throw new RuntimeException(e);
                  }
              }
              return tokenizer.nextToken();
          }
          public int nextInt() {
              return Integer.parseInt(next());
          }
          public long nextLong() {
              return Long.parseLong(next());
          }
          public boolean hasNext() {
              try {
                  String string = reader.readLine();
                  if (string == null) {
                      return false;
                  }
                  tokenizer = new StringTokenizer(string);
                  return tokenizer.hasMoreTokens();
              } catch (IOException e) {
                  return false;
              }
          }
      }
      static InputReader in = new InputReader(System.in);
      static PrintWriter out = new PrintWriter(new OutputStreamWriter(System.out));
  
      public static void main(String[] args) {
          int t = in.nextInt();
          while (t -- > 0) {
              solve();
          }
          out.close();
      }
      static void solve() {
          int n = in.nextInt();
          int k = in.nextInt();
          int[] arr = new int[n];
          for (int i = 0; i < n; i++) {
              arr[i] = in.nextInt();
          }
          long answer = Long.MIN_VALUE;
          for (int i = Math.max(0, n-250); i < n; i++) {
              for (int j = Math.max(0, n-250); j < i; j++) {
                  answer = Math.max(answer, (long) (i+1) * (j+1) - (long) k * (long)(arr[i] | arr[j]));
              }
          }
          out.println(answer);
      }
  }
  