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 P3 {
     public static void main(String[] args) {
        FastIO io = new FastIO();
        int t = io.nextInt();
        while (t --> 0) {
           int n = io.nextInt(), k = io.nextInt();
           long[] array = new long[n];
           for (int i=0; i<n; i++) {
              array[i] = io.nextInt();
           }
           long max_value = Long.MIN_VALUE;
           for (long i=n; i>0; i--) {
              for (long j=i-1; j>0; j--) {
                 if ((i)*(j) < max_value) { 
                    break; 
                 }
                 else {
                    max_value = Math.max(max_value, ((i) * (j)) - (k * (array[(int)i-1] | array[(int)j-1])));
                 }
              }  
           }
           io.println(max_value);
        }
        io.close();
     }
     static class FastIO extends PrintWriter {
          BufferedReader br;
          StringTokenizer st;
   
          public FastIO() {
              super(System.out);
              br = new BufferedReader(new InputStreamReader(System.in));
          }
   
          public String next() {
              try {
                  while (st == null || !st.hasMoreTokens()) {
                      st = new StringTokenizer(br.readLine());
                  }
                  return st.nextToken();
              } catch (Exception e) {
                  return null;
              }
          }
   
          public int nextInt() {
              return Integer.parseInt(next());
          }
   
          public double nextDouble() {
              return Double.parseDouble(next());
          }
   
          public long nextLong() {
              return Long.parseLong(next());
          }
   
          public void close() {
              try {
                  br.close();
              } catch (IOException e) {
                  e.printStackTrace();
              }
              super.close();
          }
      }
  
  }