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 Main {
      
      public static void main(String[] args) throws IOException {
          Scanner scn = new Scanner(System.in);
          OutputWriter out = new OutputWriter(System.out);
          // Always print a trailing "\n" and close the OutputWriter as shown at the end of your output
          
          // example:
          int t=scn.nextInt();
          for(int i1=0;i1<t;i1++){
              int n=scn.nextInt();
              long k=scn.nextInt();
              long[] a=new long[n+1];
              for(int i=1;i<=n;i++){
                  a[i]=scn.nextInt();
              }
              long ans=Integer.MIN_VALUE;
              for(int i=n;i>=Math.max(1,n-201);i--){
                  for(int j=i-1;j>=Math.max(1,n-201);j--){
                      long val=(long)(i)*j-k*(a[i]|a[j]);
                      if(val>ans){
                          ans=val;
                      }
                  }
              }
              out.print(Long.toString(ans)+"\n");
          }
          
          out.close();
      }
  
      // fast input
      static class Scanner {
          public BufferedReader reader;
          public StringTokenizer tokenizer;
  
          public Scanner(InputStream stream) {
              reader = new BufferedReader(new InputStreamReader(stream));
              tokenizer = null;
          }
  
          public String next() {
              while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                  try {
                      String line = reader.readLine();
                      if (line == null)
                          return null;
                      tokenizer = new StringTokenizer(line);
                  } catch (Exception e) {
                      throw(new RuntimeException());
                  }
              }
              return tokenizer.nextToken();
          }
  
          public int nextInt() { return Integer.parseInt(next()); }
          public long nextLong() { return Long.parseLong(next()); }
          public double nextDouble() { return Double.parseDouble(next()); }
      }
  
      // fast output
      static class OutputWriter {
          BufferedWriter writer;
  
          public OutputWriter(OutputStream stream) {
              writer = new BufferedWriter(new OutputStreamWriter(stream));
          }
  
          public void print(int i) throws IOException { writer.write(i); }
          public void print(String s) throws IOException { writer.write(s); }
          public void print(char[] c) throws IOException { writer.write(c); }
          public void close() throws IOException { writer.close(); }
      }
  
  
  }
  