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 A735B {
      public static void main(String[] args) {
          JS scan = new JS();
          int t = scan.nextInt();
          while(t-->0){
              int n=  scan.nextInt();
              long k = scan.nextInt();
              int[] arr= new int[n];
              for(int i = 0;i<n;i++){
                  arr[i] = scan.nextInt();
              }
              long best =Integer.MIN_VALUE ;
              for(long i = n;i>=Math.max(1,n-1000);i--){
                  for(long j = i+1;j<=n;j++){
  
                      long curr = i*j-k*(arr[(int)i-1] | arr[(int)j-1]);
                      best = Math.max(best,curr);
                  }
              }
              System.out.println(best);
          }
  
      }
      static class JS {
          public int BS = 1 << 16;
          public char NC = (char) 0;
          byte[] buf = new byte[BS];
          int bId = 0, size = 0;
          char c = NC;
          double num = 1;
          BufferedInputStream in;
  
          public JS() {
              in = new BufferedInputStream(System.in, BS);
          }
  
          public JS(String s) throws FileNotFoundException {
              in = new BufferedInputStream(new FileInputStream(new File(s)), BS);
          }
  
          public char nextChar() {
              while (bId == size) {
                  try {
                      size = in.read(buf);
                  } catch (Exception e) {
                      return NC;
                  }
                  if (size == -1) return NC;
                  bId = 0;
              }
              return (char) buf[bId++];
          }
  
          public int nextInt() {
              return (int) nextLong();
          }
  
          public long nextLong() {
              num = 1;
              boolean neg = false;
              if (c == NC) c = nextChar();
              for (; (c < '0' || c > '9'); c = nextChar()) {
                  if (c == '-') neg = true;
              }
              long res = 0;
              for (; c >= '0' && c <= '9'; c = nextChar()) {
                  res = (res << 3) + (res << 1) + c - '0';
                  num *= 10;
              }
              return neg ? -res : res;
          }
  
          public double nextDouble() {
              double cur = nextLong();
              return c != '.' ? cur : cur + nextLong() / num;
          }
  
          public String next() {
              StringBuilder res = new StringBuilder();
              while (c <= 32) c = nextChar();
              while (c > 32) {
                  res.append(c);
                  c = nextChar();
              }
              return res.toString();
          }
  
          public String nextLine() {
              StringBuilder res = new StringBuilder();
              while (c <= 32) c = nextChar();
              while (c != '\n') {
                  res.append(c);
                  c = nextChar();
              }
              return res.toString();
          }
  
          public boolean hasNext() {
              if (c > 32) return true;
              while (true) {
                  c = nextChar();
                  if (c == NC) return false;
                  else if (c > 32) return true;
              }
          }
      }
  }
  