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: //package MyPackage;
  import java.io.*;
  import java.util.*;
  public class MyClass {
      final static long mod = 1_000_000_007;
      final static int mini = Integer.MIN_VALUE;
      final static int maxi = Integer.MAX_VALUE;
      static long gcd(long a, long b) {
          if (b == 0) return a;
          return gcd(b, a % b);
      }
      static boolean isPrime(int n) {
          if (n <= 1)
              return false;
          else if (n == 2)
              return true;
          else if (n % 2 == 0)
              return false;
          for (int i = 3; i <= Math.sqrt(n); i += 2) {
              if (n % i == 0)
                  return false;
          }
          return true;
      }
      static int digits(long n) {
          int count = 0;
          long temp = n;
          while (temp > 0) {
              temp /= 10;
              count++;
          }
          return count;
      }
      static boolean isPalindrome(long i) {
          long originalNum = i;
          long remainder;
          long reversedNum = 0;
          while (i != 0) {
              remainder = i % 10;
              reversedNum = reversedNum * 10 + remainder;
              i /= 10;
          }
          return originalNum == reversedNum;
      }
      static long lcm(long a, long b) {
          return (a / gcd(a, b)) * b;
      }
      static void sort(long[] a) {
          ArrayList<Long> l = new ArrayList<>();
          for (long value : a) {
              l.add(value);
          }
          Collections.sort(l);
          for (int i = 0; i < l.size(); i++)
              a[i] = l.get(i);
      }
      static void sort(int[] a) {
          ArrayList<Integer> l = new ArrayList<>();
          for (int value : a) {
              l.add(value);
          }
          Collections.sort(l);
          for (int i = 0; i < l.size(); i++)
              a[i] = l.get(i);
      }
      static void reverse(int[] arr) {
          int l = 0;
          int h = arr.length - 1;
          while (l < h) {
              swap(arr, l, h);
              l++;
              h--;
          }
      }
      static String reverse(String s) {
          StringBuilder res = new StringBuilder(s);
          return res.reverse().toString();
      }
      static long fact(long n) {
          long res = 1, i;
          for (i = 2; i <= n; i++)
              res *= i;
          return res;
      }
      static void swap(int[] arr, int i, int j) {
          int temp = arr[i];
          arr[i] = arr[j];
          arr[j] = temp;
      }
      static class FastReader {
          BufferedReader br;
          StringTokenizer st;
  
          public FastReader() {
              br = new BufferedReader(new InputStreamReader(System.in));
          }
  
          String n() {
              while (st == null || !st.hasMoreElements()) {
                  try {
                      st = new StringTokenizer(br.readLine());
                  } catch (IOException e) {
                      e.printStackTrace();
                  }
              }
              return st.nextToken();
          }
  
          int nint() {
              return Integer.parseInt(n());
          }
  
          float nfloat() {
              return Float.parseFloat(n());
          }
  
          long nlong() {
              return Long.parseLong(n());
          }
  
          double ndouble() {
              return Double.parseDouble(n());
          }
  
          int[] narr(int n) {
              int[] a = new int[n];
              for (int i = 0; i < n; i++) a[i] = nint();
              return a;
          }
  
          int[][] narr(int n, int m) {
              int[][] a = new int[n][m];
              for (int i = 0; i < n; i++)
                  for (int j = 0; j < m; j++)
                      a[i][j] = nint();
              return a;
          }
  
          String nline() {
              String str = "";
              try {
                  str = br.readLine();
              } catch (IOException e) {
                  e.printStackTrace();
              }
              return str;
          }
      }
      public static class Pair {
          int a;
          int b;
  
          public Pair(int a, int b) {
              this.a = a;
              this.b = b;
          }
      }
      public static void main(String[] args) {
          FastReader sc = new FastReader();
          PrintWriter out = new PrintWriter(System.out);
          int t = sc.nint();
          while(t-- > 0) {
              int n = sc.nint();
              int k = sc.nint();
              int[] arr = sc.narr(n);
              long max = Long.MIN_VALUE;
              for(int i = n - 1; i >= Math.max(0, n - 105); i--) {
                  for(int j = i - 1; j >= Math.max(0, n - 105); j--) {
                      max = Math.max(max, (long) (i + 1) * (j + 1) - (long) k * (arr[i] | arr[j]));
                  }
              }
              out.println(max);
          }
          out.flush();
          out.close();
      }
  }