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.BufferedReader;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.io.PrintWriter;
  import java.util.ArrayList;
  import java.util.StringTokenizer;
  
  public class Solver {
  
      public static void main(String[] args) {
          FastReader in = new FastReader();
          PrintWriter out = new PrintWriter(System.out);
          new TaskA().solveB(in, out);
          out.close();
      }
  
      static class TaskA {
          public void solveA(FastReader in, PrintWriter out) {
              int t = in.nextInt();
  
              while (t-- > 0) {
                  int n = in.nextInt();
                  long[] array = in.nextLongArray(n);
                  long result = Long.MIN_VALUE;
  
                  for (int i = 0; i < n - 1; i++) {
                      result = Math.max(result, (array[i] * array[i + 1]));
                  }
                  out.println(result);
              }
          }
  
          public void solveB(FastReader in, PrintWriter out) {
              int t = in.nextInt();
  
              while (t-- > 0) {
                  int n = in.nextInt();
                  int k = in.nextInt();
                  long[] array = in.nextLongArray(n);
                  long max = Long.MIN_VALUE;
  
                  int start = Math.max(0, n - 2 * k);
  
                  for (int i = start; i < n - 1; i++) {
                      for (int j = i + 1; j < n; j++) {
                          max = Math.max(max, (((i + 1l) * (j + 1l)) - (k * (array[i] | array[j]))));
                      }
                  }
                  out.println(max);
              }
          }
  
          public void solveC(FastReader in, PrintWriter out) {
  
          }
  
          public void solveD(FastReader in, PrintWriter out) {
  
          }
  
          public void solveE(FastReader in, PrintWriter out) {
  
          }
      }
  
      private static long gcd(long a, long b) {
          if (a == 0) {
              return b;
          }
          return gcd(b % a, a);
      }
  
      private static long lcm(long a, long b) {
          return (a * b) / gcd(a, b);
      }
  
      private static int min(int a, int b) {
          return a < b ? a : b;
      }
  
      private static int max(int a, int b) {
          return a > b ? a : b;
      }
  
      private static int min(ArrayList<Integer> list) {
          int min = Integer.MAX_VALUE;
          for (int el : list) {
              if (el < min) {
                  min = el;
              }
          }
          return min;
      }
  
      private static int max(ArrayList<Integer> list) {
          int max = Integer.MIN_VALUE;
          for (int el : list) {
              if (el > max) {
                  max = el;
              }
          }
          return max;
      }
  
      private static int min(int[] list) {
          int min = Integer.MAX_VALUE;
          for (int el : list) {
              if (el < min) {
                  min = el;
              }
          }
          return min;
      }
  
      private static int max(int[] list) {
          int max = Integer.MIN_VALUE;
          for (int el : list) {
              if (el > max) {
                  max = el;
              }
          }
          return max;
      }
  
      private static void fill(int[] array, int value) {
          for (int i = 0; i < array.length; i++) {
              array[i] = value;
          }
      }
  
      static class FastReader {
          BufferedReader br;
          StringTokenizer st;
  
          public FastReader() {
              br = new BufferedReader(new InputStreamReader(System.in));
          }
  
          String next() {
              while (st == null || !st.hasMoreElements()) {
                  try {
                      st = new StringTokenizer(br.readLine());
                  } catch (IOException e) {
                      e.printStackTrace();
                  }
              }
              return st.nextToken();
          }
  
          int nextInt() {
              return Integer.parseInt(next());
          }
  
          long nextLong() {
              return Long.parseLong(next());
          }
  
          double nextDouble() {
              return Double.parseDouble(next());
          }
  
          String nextLine() {
              String str = "";
              try {
                  str = br.readLine();
              } catch (IOException e) {
                  e.printStackTrace();
              }
              return str;
          }
  
          int[] nextIntArray(int n) {
              int[] array = new int[n];
              for (int i = 0; i < n; i++) {
                  array[i] = nextInt();
              }
              return array;
          }
  
          long[] nextLongArray(int n) {
              long[] array = new long[n];
              for (int i = 0; i < n; i++) {
                  array[i] = nextLong();
              }
              return array;
          }
      }
  }