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 javax.swing.*;
  import java.io.BufferedReader;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.io.PrintWriter;
  import java.util.*;
  
  public class A {
      static ArrayList<Integer> [] adj;
      static ArrayList<Integer> temp;
      static int mod = (int) 1e9+7;
      static boolean[] vis = new boolean[(int)1e5];
  
      public static void main(String[] args) throws IOException {
          FastScanner s=new FastScanner();
          int t = s.nextInt();
  //        int t = 1;
          while(t-->0){
              int n = s.nextInt();
              int k = s.nextInt();
              int[] a = s.readArray(n);
              long ans=Integer.MIN_VALUE;
              for(int i=Math.max(n-300,0);i<n;i++){
                  for(int j=i+1;j<n;j++){
                      ans = Math.max(ans,(i+1)*(long)(j+1)-k*(long)(a[i] | a[j]));
                  }
              }
              System.out.println(ans);
          }
      }
  //Important
  //Dont't stick on same approach
  //Check long
  
  
  
  
      static void dfs(int i){
          vis[i]=true;
          temp.add(i);
          List<Integer> Y = adj[i];
          for(int x:Y){
              if(!vis[x])dfs(x);
          }
      }
  
      static long gcd(long a, long b) throws IOException {
          return (b == 0) ? a : gcd(b, a % b);
      }
  
      static int gcd(int a, int b) throws IOException {
          return (b == 0) ? a : gcd(b, a % b);
      }
  
      static void sortr(int[] a) {
          ArrayList<Integer> l = new ArrayList<>();
          for (int i : a)
              l.add(i);
          Collections.sort(l, Collections.reverseOrder());
          for (int i = 0; i < a.length; i++)
              a[i] = l.get(i);
      }
  
      static void sort(int[] a) {
          ArrayList<Integer> l = new ArrayList<>();
          for (int i : a)
              l.add(i);
          Collections.sort(l);
          for (int i = 0; i < a.length; i++)
              a[i] = l.get(i);
      }
  
      static void sort(long[] a) {
          ArrayList<Long> l = new ArrayList<>();
          for (long i : a)
              l.add(i);
          Collections.sort(l);
          for (int i = 0; i < a.length; i++)
              a[i] = l.get(i);
      }
  
      static class FastScanner {
          BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
          StringTokenizer st = new StringTokenizer("");
  
          String next() {
              while (!st.hasMoreTokens())
                  try {
                      st = new StringTokenizer(br.readLine());
                  } catch (IOException e) {
                      e.printStackTrace();
                  }
              return st.nextToken();
          }
  
          int nextInt() {
              return Integer.parseInt(next());
          }
  
          int[] readArray(int n) {
              int[] a = new int[n];
              for (int i = 0; i < n; i++)
                  a[i] = nextInt();
              return a;
          }
          long nextLong() {
              return Long.parseLong(next());
          }
      }
  }